Details on hundreds of prison staff were found during last week's police raids in north and west Belfast linked to IRA intelligence gathering, sources have told the BBC.

On Monday, the Northern Ireland Prison Service told staff on duty to be particularly aware of their personal security.

It is understood that files found by the police contain the names and home addresses of almost all 2,000 prison service staff.

It's a devastating blow to those officers who serve the community and have done for the past 30 years

Finlay Spratt Prison Officers' Association

The service has said it will hold talks with staff associations to see what further precautions might be taken.

Finlay Spratt from the Prison Officers' Association said it was a worrying development.

"This comes as a terrible blow to us who serve the community, all sides of the community - to discover that these groupings are still targeting and gathering information on prison officers, their families and their children," he said.

"It's a devastating blow to those officers who serve the community and have done for the past 30 years."

The move follows the appearance of two people in court who were charged with having documents likely to be of use to terrorists.

Two other people arrested during the raids in north and west Belfast on Friday are still being questioned by police.

Political crisis

The arrests and seizures of documents and computer equipment were part of a major police operation which included a raid on Sinn Fein's Stormont office.

The operation has contributed to a crisis in the political process which is threatening the future of the Northern Ireland Assembly.

The Ulster Unionist Party has called on the British Government to take action against republicans over what party leader David Trimble called "political espionage on a massive" scale.

He claimed republicans had been able to secretly monitor Northern Ireland Office communications for at least a year.

The Democratic Unionist Party has said it will withdraw from the assembly, while Sinn Fein and the SDLP have warned that if devolution collapses or is suspended, it could take years to rebuild a political settlement.