We're wrapping up our live coverage of the cyber-attacks now but here's a summary of what has happened so far:

• The total number of NHS services which have been affected stands at 39 hospital trusts with GP practices and dental services also targeted across England and Scotland
• Some 74 countries including the UK, US, China, Russia, Spain, Italy and Taiwan have reported being affected by a virus
• Theresa May said the attack was not targeted at the NHS, it was part of an international incident
•  NHS Digital has said there is no evidence patient data has been compromised

To follow updates on how the attack is affecting the NHS, see our story here and for the latest on international developments click here.

BBC health correspondent Hugh Pym says it is not clear how long the disruption to services will last but that it will almost certainly continue well beyond the weekend.

Terry Baldwin tells us:

The encryption virus attack on the NHS is commonly used against small businesses and individuals. 

As soon as this attack began, all hospitals and surgeries should have been told to shut down their computer systems to stop it spreading. Apparently this did not happen and many surgeries were told it was safe to restart their computers around 3.30 this afternoon resulting in the further spread of the virus.

This kind of attack usually causes some inconvenience or financial loss its victims but in this case it may well cause loss of life. 

Simon comments:

I work in a IT systems team in a NHS Trust. We have spent all afternoon defending and protecting staff and patients from this. Fingers crossed we will stay off the list.

What I worry about is the long term effect this will have on staff moral and their trust of major IT roll outs.

NSA whistleblower Edward Snowden tweets...

Alison tells us:

I have tried to get an urgent GP appt for a patient this afternoon.  Unable to contact surgery and when I eventually had chance to call in, GP highlighted that without computer access he couldn't order appropriate X-Rays therefore appt had to be delayed until Monday.

Ruth, Blackburn writes:

As a chemotherapy patient I have a chemo unit helpline number (in case of emergencies and queries). Due to this cyber attack (didn't know this at the time of ringing) I could not get through. The phone lines had gone down. My query was not an emergency but was related to an important prescription. This is a real problem for the hospital and mine is just an example of the chaos it is causing. This could ultimately cost lives.

Image source, Reuters

Another firm that has confirmed it has been caught out by the cyber-attack is delivery company FedEx, although it did not clarify in which territories it has been hit.

"Like many other companies, FedEx is experiencing interference with some of our Windows-based systems caused by malware," it said in a statement.

"We are implementing remediation steps as quickly as possible."

Sara describes the scene at the accident and emergency department at the University Hospital Coventry.

"It was extremely busy and hot and there were hardly any seats. The queue to be registered went out the door. 

"They told people as they queued that there was a delay as the system was down. 

"I am still waiting to be seen for an X-ray. I hope they are able to do it as obviously it will be done using a computer."

Image source, Sara

About 1,000 computers at the Russian Interior Ministry have been affected by the cyber-attack, spokeswoman Irina Volk told Interfax news agency.

The news agency quoted the ministry as saying it had "localised the virus" and work was under way to destroy it.

Interfax added the the ministry had said servers were not affected "owing to the use of other operating systems and homemade servers with Russian Elbrus processors". 

An anonymous NHS staffer tells us: 

"Absolute carnage in the NHS today. Two Hyperacute stroke centres (the field I work in) in London have closed as of this afternoon. Patients will almost certainly suffer and die because of this.

"Had a patient that needed urgent neurosurgery referred, but unable to look at scans - stroke care is absolutely dependent on IT systems and joined up systems."

The NHS in Wales has reported there are no issues with malware on any of its systems.

A Welsh Government spokesperson said: "We have had no reported cyber incidents affecting NHS Wales but are monitoring the situation closely."

BBC Radio York

York Teaching Hospitals NHS Foundation Trust says no operations have been cancelled as a result of the attack and surgeries will be continuing as usual over the weekend.

But some MRI scans will be cancelled.

There have been no issues with sterilising equipment 

Hospitals in Scarborough, Bridlington, York and Malton and Selby have had their email systems taken down.

Community services in Malton and Selby are also affected.

The trust said the attack "is having an impact - things are taking longer". 

Plans are in place if the virus spreads so that the hospital can continue to run, it added.

The hospital pharmacy is operating as usual and staff are still looking at if any routine appointments or scans need to be cancelled over the weekend.   

In Catterick, Helmsley, Pickering, Malton and York breast screening services have been cancelled.  

BBC health reporter Philippa Roxby reminds us that the NHS has faced cyber security issues in the past.

What is ransomware, how does it work and what can be done to stop it? The BBC takes a look at the WannaCry virus.

Dominic Casciani
Home Affairs Correspondent

The NHS ransomware attack is the biggest test (that we know of) for the National Cyber Security Centre. What’s that? It’s the UK’s frontline. 

Cyber attacks are ranked among the top threats faced by the UK - but successive governments have been at odds and ends over how best to confront them. So much so in fact that MPs recently warned that ministers had taken too long to consolidate an alphabet soup of agencies. 

The NCSC is supposed to be helping put an end to all that. Its first chief, Ciaran Martin, said at the official opening in February that he wanted those who electronically attack the UK to “think of us as the hardest of targets”. 

Today clearly shows they have a lot of work ahead. 

While they get on with it, here’s a link to the NCSC guide on how organisations - big and small - can protect themselves from ransomware, external.  

Image source, NCSC

Dr Ayesha Malik posted this uplifting comment on WhatsApp:

"I work as a GP in South London. It's times like these that you realise how the NHS staff come together to tackle adversity. Good old fashioned medicine and handwritten paper prescriptions - cybercrime won't beat us yet".

Computers in thousands of locations have apparently been locked by a program that demands $300 (£230) in Bitcoin.

Bitcoin is a virtual currency, which is purchased with real money. 

Image source, Royal Berkshire NHS Foundation Trust

The Royal Berkshire Hospital in Reading says access to patient records has not been affected but there are issues with the system it uses for discharging people.

Staff have reverted to using paper for these and some test results but maintain their paper-based system is "tried and tested" and that patient safety has not been compromised.

However, the hospital does warn that patients should expect some delays to their care.