Simon Byrne had faced a motion of no-confidence in his leadership from the Democratic Unionist Party (DUP).

DUP leader Sir Jeffrey Donaldson had said: "Confidence in the chief constable has been eroded, both amongst the wider public but, significantly, also amongst serving PSNI officers and staff.

"In light of that, we believe that a change of leadership is required."

Mr Byrne had been under pressure after a data breach last month where information on about 10,000 officers and staff was accidentally disclosed online.

The breach involved the surname, initials, the rank or grade, the work location and departments of all PSNI staff, but did not involve the officers' and civilians' private addresses.

The data is thought to now be in the possession of dissident republicans.

Mr Byrne had on Tuesday been expected to appear before an evidence session of the Northern Ireland Affairs Committee which is investigating the data breach.

His resignation also comes after a row erupted last week when High Court judge ruled two junior officers were unlawfully disciplined for an arrest made at a Troubles commemoration event in 2021.

The judge, Mr Justice Scoffield, said they had been disciplined to allay a threat that Sinn Fein could withdraw its support for policing.

Sinn Fein has insisted there was no such threat.

Mr Byrne had insisted he would not quit following an emergency meeting of the Northern Ireland Policing Board on Thursday and indicated he was considering an appeal against the court ruling.

That statement was met by anger from the Police Federation, that represents rank-and-file officers, with its chair Liam Kelly expressing "disbelief and anger" at the chief constable's remarks.

Mr Byrne has since been facing growing pressure, with both rank-and-file officers and civilian staff mulling confidence votes in his leadership.

On Friday, Mr Donaldson confirmed his party had submitted a motion of no-confidence in Mr Byrne to the Policing Board, which is the oversight body for the PSNI.

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