Northern Ireland's top police officer apologized after data related to thousands of police officers and staff was leaked online.

"An early worst-case scenario that we have been dealing with is that third parties would attempt to get this data to intimidate, corrupt or indeed cause harm to our officers and staff,'' Police Service of Northern Ireland (PSNI) Chief Constable Simon Byrne said after he attended an emergency meeting of the Northern Ireland Policing Board on Thursday. 

Personal information related to more than 10,000 officers was accidentally shared online through two leaks.

The leaks are highly sensitive in Northern Ireland, where officers are still sporadically targeted by dissident groups in bomb and gun attacks. This is despite a 1998 peace deal that largely ended three decades of sectarian violence.

"We are now aware that dissident republicans claim to be in possession of some of this information circulating on WhatsApp,"  Byrne said.  

He added authorities are "advising officers and staff about how to deal with that and any further risk they face.

How the information was leaked

The data leak took place on Tuesday police responded to a Freedom of Information request that sought to know about the number of police officials and staff working for the Police Service of Northern Ireland.

The reply of the police — which stayed public for over two hours — accidentally also included the surnames, initials, location and departments for all their employees.

A second breach that occurred in July, in which a laptop containing confidential files like a spreadsheet of details about 200 serving police officers, came to light on Wednesday.

The information made public also includes details about 40 officers who work for Britain's domestic intelligence body MI5 in Northern Ireland.

Byrne described it as an "industrial scale" data breach.

In March, the UK increased the terrorism threat level to "severe" in response to an assassination attempt on senior police officer John Caldwell, claimed by the New IRA.

In the wake of the breach, the PSNI is considering relocating some officers to new locations, Byrne said.

mfa/lo (AP, AFP, Reuters)