Chief Constable Simon Byrne says information mistakenly released in a major data breach is in the hands of dissident republicans
Details of 10,000 officers and civilian staff were mistakenly released on a spreadsheet
Thousands of officers have raised concerns about their safety
Police investigate a document containing redacted information from the list posted on a wall
This is the end of our live coverage of Simon Byrne's press conference.
You can continue to follow this story on the BBC News NI website, BBC Radio Ulster and Newsline on BBC One Northern Ireland.
We've just had an update from PSNI Chief Constable Simon Byrne on the major data breach that emerged last week - here's what he said:
Image source, Pacemaker
Julian O'Neill
BBC News NI Home Affairs Correspondent
If dissident republicans have this information, then the obvious question is: What does this mean for staff, officers and civilian personnel?
The chief constable says they would likely use it to generate fear among officers and staff and also use it, if they can, to target staff.
Simon Byrne says measures will be taken to address the risks.
Image source, PA MediaThe big difficulty the PSNI faces is the sheer enormity of this.
Mr Byrne talks about a sort of triage system where the PSNI will assess the safety of individuals.
We’ve got 10,000 employees, all of whom feel varying degrees of anxiety.
How do you evaluate that risk to so many people, in real time and as quickly as possible?
The Police Federation for Northern Ireland says although it assumed information from the data breach would find its way to dissident republicans, it was, nevertheless, a "deeply worrying development".
"It makes it all the more imperative for each and every colleague to exercise maximum vigilance," the federation's chairman Liam Kelly says.
"We must do all we can to frustrate and prevent attacks on our colleagues and their families."
He says PSNI officers were "resilient and resourceful".
"They must call on all their training and professionalism to counter this ugly consequence of a monumental data breach."
Asked about the £500 safety money for civilian staff, the chief constable says it is a matter that has been under review for some time with the Department of Justice and adds that the PSNI are working actively with the UK government.
He says the PSNI has the "green light" for support if new measures are needed to keep staff safe.
He says if further finances are needed to protect the workforce and staff he is "confident the UK government is standing by for the ask".
The chief constable's press conference has just finished.
You can watch it back by clicking the video link at the top of this page.
Simon Byrne says dissident republicans have the information from the data breach
Simon Byrne says at the start of the day there were 45 members of PSNI staff the organisation “hadn’t caught up with" to discuss the breach, adding that things were moving quickly.
He says the sheer volume of staff involved makes it difficult “to triage and ring people back”.
He says contact and face-to-face meetings were continuing to be organised and that the details of retired colleagues were not part of the breach.
Byrne says a range of cyber specialists across the policing system are strongly supporting the PSNI in dealing with this "unprecedented" incident.
Measures are in place to reassure and advise the workforce on what this risk means for them, he adds.
He says they will continue to liaise with the Policing Board and the UK government and other partners as they develop their response to the matter.
Chief Constable Simon Byrne says "we are not seeing any movement of officers" out of the PSNI, contrary to reports.
He pays tribute to his officers' "courage and resolve" since the breach.
The chief constable says the safety of all his officers remains his top priority.
The press conference begins with Chief Constable Simon Byrne taking to the podium.
Byrne begins by saying the workforce data set is in the hands of dissident republicans.
"They will use the list to generate fear and uncertainty and intimidate or targeting officers and staff," he says.
He adds they are working around the clock to assess and mitigate this risk.
You can watch the press conference live by clicking play at the top of this page.
More than 300 police officers were killed during the Northern Ireland Troubles and since the formation of the Police Service of Northern Ireland Constables Stephen Carroll and Ronan Kerr have been killed while on duty.
Dissident republicans have targeted other officers, including senior detective John Caldwell, who was shot and critically injured while coaching youth football in Omagh, County Tyrone, in February.
Police officers are advised to take protective measures to guard against the threat of attack, both off and on duty.
Some have told BBC News NI they do not tell friends and family about their jobs, such is the level of threat.
Image source, PA MediaJohn Caldwell was shot and injured at a youth sports complex in Omagh in February
Last week it emerged the details of 10,000 police staff, from officers to civilian workers, had been mistakenly released as part of a response to a freedom of information request.
The spreadsheet contained surnames and initials, as well as staff ranks. It did not identify private addresses.
Chief Constable Simon Byrne said he was deeply sorry and that the release of information was on an industrial scale.
In a separate incident, police said a laptop containing information about staff had been stolen from the car of an officer in July in Newtownabbey, County Antrim.
This was subsequently wiped remotely, the PSNI added.
Good evening and welcome to live coverage of the PSNI chief constable’s latest update on the data breach.
Simon Byrne is due to address the media shortly.