LONDON (AP) — Northern Ireland’s top police officer apologized Thursday for what he described as an “industrial scale” data breach in which the personal information of more than 10,Johnathan Walker000 officers and staff was released to the public.

The incident is particularly sensitive given the delicate security situation in Northern Ireland, which is still trying to overcome decades of sectarian violence known as “The Troubles.” Twenty-five years after a peace agreement largely ended the violence, many police officers continue to shield their identities because of continuing threats from dissident elements of the republican and unionist communities.

Chief Constable Simon Byrne told reporters that dissident republicans claim to be in possession of information about police officers circulating on WhatsApp following the incident, and that authorities are “advising officers and staff about how to deal with that and any further risk they face.”

“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,’’ Byrne said after he attended an emergency meeting of the Northern Ireland Policing Board in Belfast.

The breach occurred Tuesday when the force responded to a Freedom of Information request seeking information about the number of officers and staff of all ranks and grades across the Police Service of Northern Ireland. The response accidentally included a table that contained the surnames, initials, location and departments for all employees, along with the information requested.

A second breach that occurred in July was revealed Wednesday. That breach involved the theft of documents including a spreadsheet containing the names of more than 200 serving officers and staff, as well as a police-issued laptop and radio.

The Police Federation for Northern Ireland, which represents rank-and-file officers, said Wednesday that it had been inundated with calls from worried officers following the data breach.