The leadership of the Police Service of Northern Ireland (PSNI) has been urged to give a “full response” following a major data blunder.

PSNI Chief Constable Simon Byrne cut short a family holiday to return to Belfast to answer questions about the data breach, which saw some details of around 10,000 officers and staff published online for a number of hours on Tuesday.

Details of another breach following the theft of documents and a laptop from a car in Newtownabbey in July emerged on Wednesday.

Scores of officers have expressed concern for their safety in Northern Ireland where police are under threat from terrorists, with the current assessed level of threat at severe, meaning an attack is highly likely.

Mr Byrne answered questions from politicians in a closed session of the Northern Ireland Policing Board on Thursday before making a brief statement to media.

He revealed that dissident republican terrorists had claimed to be in possession of some of the data, but said that claim had not yet been verified.

Detective Chief Inspector John Caldwell was left seriously injured in February after a gun attack by dissidents at a sports centre in Co Tyrone.

It is hard to think of a more pressing issue for Catholic officers and staff than the data breaches which have come to light this week

The Threat Management Assessment Group has been set up by the PSNI for those concerned about risk. It had had 600 referrals by Thursday evening.

Mr Byrne met the Nipsa trade union which represents staff support officers on Friday morning.

Speaking after the meeting Tracy Godfrey said she was alarmed to hear the number of requests for support from the group had risen to 900 overnight.

“I believe that number will climb, but they have got processes in place to deal with it. It’s just an awful lot of people with a lot of concerns,” she told the BBC.

The Catholic Police Guild, which represents a significant number of Catholic members of the PSNI, has called for a full response from senior ranks.

Guild chairperson Superintendent Gerry Murray said was seeking reassurance from the chief constable and an urgent meeting.

He referred to particular difficulties faced by Catholic members of the PSNI, and expressed concern the data breaches could impact on future recruitment.

Catholics have historically been under-represented in police in Northern Ireland. When the former police force the RUC transitioned to become the PSNI in 2001, a temporary recruitment measure was used to welcome even numbers of Catholic and Protestant officers, referred to as 50/50 recruitment.

“Our guild was formed to provide a support service within the PSNI for Catholic members, and to raise issues which impact on their work within the PSNI,” he said.

“It is hard to think of a more pressing issue for Catholic officers and staff than the data breaches which have come to light this week.

“Everyone understands the particular difficulties faced by Catholic members of the PSNI and indeed the implications of this for potential new recruits from the Catholic community.”

Mr Murray said the guild’s members had expressed genuinely held concerns over the release of the information.

“They are worried for themselves and in many cases for their family members,” he said.

“As chairman of the guild I am also concerned about the impact on future recruitment of young Catholics into the police service.

It is important that the Police Service acts quickly and comprehensively to win back and retain the confidence of serving officers and staff. This applies particularly to colleagues from the Catholic community

“We are seeking an urgent meeting with the chief constable and senior colleagues and we want to be assured that the data breach will be fully and quickly investigated and procedures put in place to ensure it cannot happen again.”

He added: “Catholic officers and staff who feel vulnerable need to be supported in protecting themselves, their families and their homes.

“The Police Service must acknowledge and take account of the particular sensitivities of the Catholic members of the force.

“The community background of police officers and staff has to be given the proportionate weight when considering the implications of this data breach on serving officers.

“It is important that the Police Service acts quickly and comprehensively to win back and retain the confidence of serving officers and staff. This applies particularly to colleagues from the Catholic community.”