The details of almost 10,000 officers and civilian staff were wrongly included in a freedom of information response earlier this month.

City of London Police Assistant Commissioner Peter O’Doherty, who has responsibility for leading the UK policing response to fraud and cyber crime, is to head up the investigation.

Policing Board chair Deirdre Toner announced the review after a meeting with senior officers including Chief Constable Simon Byrne.

Mr Byrne left the summit without speaking to the media.

Watch: PSNI Chief Constable leaves through back door following policing board meeting over data leak

He said in a statement the review would “provide answers”.

“I recognise the gravity of the situation and the challenges ahead,” he added.

Ms Toner said the main breach and subsequent, smaller breaches had “damaged the reputation of the service”.

She described the meeting with the chief constable as “crunchy” and stressed the board would continue holding the police to account.

Of Mr Byrne’s refusal to answer questions, she said: “We have different roles about where we are operationally.

“The chief constable and his team have responsibilities. Our job is to make sure that we are an accountable body.”

Policing Board vice-chair Edgar Jardine said the watchdog was “unanimous” in its support for the chief constable.

“We have been in touch with the [Police] Federation and Nipsa. We had nine organisation representatives in today and no one was challenging that position,” he added.

SDLP Policing Board member Mark H Durkan warned the leadership team had a long way to go to restore public confidence.

He said: “We have heard from many officers about how badly they have been impacted by these data breaches, and it has further undermined hard-won public confidence.

“Measures needed to restore it include ensuring this review is robust, follows a strict timeframe and the resources are made available to implement its recommendations as a matter of urgency.

“I also cannot understand why police did not appear before the media at a time when confidence is low around policing, particularly when, despite being challenging, the general tone of the meeting was constructive.”

Policing Board member Mike Nesbitt backed Mr Byrne to remain in post for now.

He said: “An unplanned change strikes me as simply adding to an already deeply uncertain situation.

“However, this should not be regarded as a blank cheque. Time must tell, quickly.”

A Belfast Telegraph poll published this week showed only 16% of people had complete faith in Mr Byrne’s leadership, with 60% lacking confidence.

“Confidence can never be unconditional or a blank cheque,” Mr Jardine said.

“We have commissioned a thorough review. The board will deal with the consequences whenever we get the findings.”

Ms Toner said the review would be carried out jointly alongside the PSNI, adding this input was needed because “policing knows policing”.

“The review team has no relationship with the PSNI. National experts are leading it from digital services,” she explained.

“The board will be alongside this, and as that work progresses we will be looking at it independently. We will have an opportunity to challenge where we have concerns.

“The report is jointly commissioned by the PSNI and the board. We expect the review lead to report simultaneously.

“It’s not that confidence can’t change, but we need to focus on the systems, not individuals.”

When asked if any police officers or staff had been moved from their roles in response to the crisis, Ms Toner said: “Today’s meeting wasn’t about that. It was about the strategic oversight of how we move forward.”

The independent review will publish an initial report within a month and a full report by the end of November.

The probe is expected to investigate the actions that led to the breach and any management or governance factors that allowed it to happen.

It will also look at ways to improve procedures in the future.

The Policing Board said it hoped the review would “restore confidence in the PSNI’s approach to information security management”.

While the information was taken down from the website where it was published within a matter of hours, it has since spread online.

In a second breach on July 6, a police laptop and radio and a document containing the names of more than 200 staff were stolen from a vehicle at a shopping centre in Newtownabbey.

There was a third breach on August 17 after a PSNI laptop and a police officer’s notebook fell from the roof of a moving car.