Up to 200 Special Branch officers have been urged to increase personal security in the wake of a raid on a Northern Ireland police station.
As police continue to blame the Provisional IRA for stealing intelligence files during a break-in at the Castlereagh complex in east Belfast, sources confirmed a fresh risk assessment has been carried out.
One confirmed: "They have been told to step up their security."
Sensitive documents, including details on informants and their police handlers, were snatched from a Special Branch office during the St Patrick’s Day robbery.
One of the nine people arrested in connection with the break-in has been remanded in custody after being accused of having information likely to be useful to terrorists.
The charge against him does not relate to the files stolen from Castlereagh.
Sinn Fein has called on Prime Minister Tony Blair to step in and call off the searches on republican houses, claiming they are being scapegoated for an act carried out by shadowy intelligence agencies
.