As many as 650 people have died after being given powerful painkillers inappropriately, it has been found.
The lives of 456 patients were shortened by the use of opiates and the panel found another 200 were "probably similarly affected".
The report follows several inquiries into the prescribing of sedatives at Gosport War Memorial Hospital.
Health and social care secretary, Jeremy Hunt, apologises to families for what they have been through.
A fresh review, led by former Bishop of Liverpool James Jones, spoke to more than 100 families and analysed 800 death certificates.
Relatives said they hoped it would end their "harrowing" wait for answers.
Speaking at a press conference, former Bishop of Liverpool James Jones, who led Gosport Independent Panel, said the families were "enormously appreciative" of what the report said.
Bishop Jones said: "Their reaction was understandably emotional.
"If I quote anonymously, one of the family's said to me that it was such a relief to hear what they had thought for so long."
Image source, PACharlie Massey, Chief Executive of the General Medical Council (GMC), said: "Our thoughts are with the families of those who lost their loved ones, following simply unacceptable treatment at Gosport War Memorial Hospital.
"Patients and their families were clearly let down by the system, and that is not good enough. This has been an extremely difficult and protracted process for each family involved.
"We welcome the work that Bishop James Jones and his panel carried out to oversee the maximum possible disclosure of information around the care of patients at the hospital over two decades.
"We will be studying the report carefully to identify learning points. We are committed to taking any further action necessary in light of information revealed by this report."
Janet Davies, chief executive of the Royal College of Nursing, said: "This report makes for very sober reading for everybody involved in the care of patients.
"Although there can be no meaningful recompense for the affected patients and their families, today's report will offer some comfort to those still grieving.
"Nursing as a profession must work hard to seek out lessons from Gosport and we expect that approach to be shared by regulators and the health and care system.
"The report is right to praise the bravery shown by the nurses who raised concerns. It highlights how difficult it can be for nursing staff to challenge the decisions taken by others.
"A culture of candour is key to ensuring these events are never repeated and the parts of the NHS that fall short in this area must learn from the best."
Gosport Hospital statement
House of Commons
Parliament
Image source, HoCLiberal Democrat Norman Lamb, who has been campaigning on this issue, thanks the secretary of state for allowing this inquiry back in 2013, after trusting Mr Lamb's judgement on the issue.
He asks if Mr Hunt agrees that the UK should overcome the problem of different inquiries and inquests which prevents timely release of information. There needs to be a mechanism for families to complain, he adds.
Mr Hunt pays tribute to Norman Lamb says that "his instincts have been proved absolutely right" after not following advice from Department for Health staff.
"At the heart is this problem that we didn't listen to families early enough," he adds.
Gosport Hospital statement
House of Commons
Parliament
Image source, HOCThe Speaker has reminded the House that some of the MPs whose constituencies are most affected by the scandal at Gosport Hospital who will not be able to speak in this debate because of their positions on the government frontbench.He acknowledges their presence in the House.
Only backbenchers can ask questions after the minister's and shadow minister's statements.
The affected MPs are Caroline Dinenage for Gosport, Penny Mordaunt for Portsmouth North, Suella Braverman for Fareham and George Hollingbery for Meon Valley.
Gosport Hospital statement
House of Commons
Parliament
Image source, HoCThe SNP's Martyn Day says "these are truly horrific events" and he says the inquiry has taken far longer than the original forecast of two years.
He says he "sincerely hopes" that this will be the beginning of justice for the families affected.
Mr Hunt says one of the big questions is where families should turn if they have concerns.
Gosport Hospital statement
House of Commons
Parliament
Health Secretary Jeremy Hunt says he agrees with everything that has been said by the shadow health secretary.
The big question is not how this could have happened once, but "how it could have been allowed to go on for so long without being stopped", he says.
The poor treatment of whistleblowers and ignoring of families is "wrong", he adds.
He says he believes that the NHS is more "transparent and open," but he does not "by any means" "believe that we are there".
He asks if police forces are really getting the information they need to proceed with their investigations.
Gosport Hospital statement
House of Commons
Parliament
Image source, HoCShadow health secretary Jonathan Ashworth welcomes the tone of Jeremy Hunt's statement and, he too, pays tribute to Norman Lamb who has campaigned on this issue. He thanks those who took part in the report.
He says it is a "substantial" 400 page report which will take time to absorb.
He says the questions that remain on why concerns went unheeded, especially when the first junior nurse raised her worries in 1991. He asks why patients were handled in a way to limit damage against the organisation.
There are questions for Hampshire Constabulary, he adds, asking why 92 patient deaths were investigated without any prosecutions being brought.
"Families were too readily dismissed, it's shameful," he says.
He asks for reassurances that relevant authorities will investigate and take this further.
He asks what tighter lessons there are for medicines in the NHS.
Jeremy Hunt told MPs at Prime Minister's Questions that "any further action by the relevant criminal justice and health authorities must be thorough, transparent and independent".
He suggested that Hampshire Constabulary should consider whether another force should be brought in.
Following the publication of the report, a Crown Prosecution Service (CPS) spokesperson said: “We will consider the content of the report and will take any appropriate steps as required.”
The CPS were involved after Hampshire Constabulary passed three separate investigations to them between 1998 and 2006.
Those investigations by the police force have been described in the report as "consistently poor".
Health and Social Care Secretary, Jeremy Hunt, says there was a "catalogue of failures" from the Department of Health and the local authorities, police force and NHS.
He says he can "at least, apologise" for what happened and what the families have been through.
He says that had the establishment listened when junior staff and families spoke out, as many deaths "would not have happened".
"It is a lonely place seeking answers that others wish you were not asking," he says.
Image source, PAHe pays tribute to former health minister Norman Lamb, who has been campaigning on this issue both in and out of office.
The report took a "families first" approach, meaning that they got advance sight of the report before it was laid before Parliament this morning, he states.
He asks if there was an "institutional desire" to blame the issues "on one rogue doctor" for the sake of protecting institutional reputations.
He adds that the government has changed how it deals with deaths in hospitals, and he will come back to the Commons with a fuller response when more information is known.
Image source, PALiberal Democract MP Norman Lamb, who announced the launch of the inquiry as care minister in 2014.
He said: "The findings are shocking and devastating in equal measure - both in terms of the 456 patients who had opioids prescribed inappropriately, but also the disgraceful closing of ranks to stop families from getting to the truth.
"Never again must we allow a situation to develop where ordinary people are left in the dark, ignored and not listened to.
"We must ensure that there is some mechanism to guarantee that whenever allegations of wrongdoing are raised by people, they are listened to and their concerns are investigated thoroughly.
"I will be asking to meet with the Prime Minister, together with those families affected, to discuss the implications of this report."
The report said the quality of Hampshire Constabulary’s three investigations was "consistently poor".
The panel found officers had a mindset of seeing family members who complained as "stirring up trouble" while seeing the hospital as the place to go for guidance and assurance during their inquiries.
The force carried out three investigations between 1998 and 2006.
The prime minister, Theresa May, has described the findings of the Gosport Independent Panel as "tragic and deeply troubling" and spoke of the "unimaginable heartache of the families of all concerned".
She paid tribute to Norman Lamb, who launched the inquiry in 2014.
She added that Jeremy Hunt, the health and social care minister, would shortly be making a statement.
Chief Constable Olivia Pinkney said: "Today is about the relatives of those who died at Gosport War Memorial Hospital and their opportunity to obtain a better understanding of what happened to their loved ones.
"The report that has been published by the Gosport Independent Panel examines the concerns raised by families over a number of years about the initial care of relatives at Gosport War Memorial Hospital and the subsequent investigations by a number of agencies into their deaths.
"Hampshire Constabulary carried out three police investigations between 1998 and 2006. This involved detailed professional assessment by a number of independent medical experts and the evidence was presented to the Crown Prosecution Service and Treasury Counsel, which concluded that the evidential test for prosecution as set out in the Code for Crown Prosecutors was not met.
Image source, PA"We have co-operated fully with the Panel's enquiries and shared with them more than 25,000 documents containing 100,000 pages of information.
"Now that the report has been published and shared with us, we will take the time to read its findings carefully. We will assess any new information contained within the report in conjunction with our partners in health and the Crown Prosecution Service in order to decide the next steps."
The hospital records to which the panel had privileged access demonstrated that hundreds of patients died through prescribing and administering opioids without medical justification.
The panel is now calling upon the Secretary of State for Health and Social Care, the Home Secretary, Attorney General and the chief constable of Hampshire police and the relevant investigative authorities to recognise the significance of what is revealed about the circumstances of deaths at the hospital and to act accordingly.
Gosport MP Caroline Dinenage said the report had highlighted many “failures” by the authorities to properly investigate what was happening at the hospital.
She said all the organisations involved must look closely at the full report and urged the government to take action if there were cases to answer.
She said: “I can’t even imagine what the families must be going through – it’s absolutely heart-breaking.
“There are so many unanswered questions and they deserve to be answered.
“Everybody needs to look at this document very carefully.”
Gosport hospital deaths: Prescribed opioids 'shortened 456 lives'
The Gosport Independent Panel was chaired by James Jones, former Bishop of Liverpool.
It was set up in 2014 by the then Health Minister Norman Lamb after years of campaigning by victims' relatives.
Bishop Jones said the report shows "how the healthcare organisations failed to recognise what was happening at the hospital and failed to act to put it right; how the police investigations were limited in their depth and in the range of possible offences pursued; how the process of the General Medical Council and the Nursing and Midwifery Council were delayed; and how the inquests proceeded."
Image source, PASpeaking to at a press conference, he said: "The families now deserve every support in absorbing what has been revealed and in whatever process may now follow.
"Throughout the relatives have showed remarkable tenacity and fortitude in questioning what happened to their loved ones.
The Gosport Independent Panel investigation into hundreds of suspicious deaths at the hospital, which was first launched in 2014, examined more than one million pages.
It revealed "there was a disregard for human life and a culture of shortening lives of a large number of patients" at the Hampshire hospital.
The report added: "There was an institutionalised regime of prescribing and administering 'dangerous doses' of a hazardous combination of medication not clinically indicated or justified, with patients and relatives powerless in their relationship with professional staff."
When relatives complained or raised concerns, they were "consistently let down by those in authority - both individuals and institutions".
Image source, PA