A break-in at one of the most secure police stations in Northern Ireland is nothing less than a "Watergate-type event," a senior nationalist politician has said.
A number of files are believed to have been taken from a Special Branch office at Castlereagh police station, east Belfast, on Sunday evening after three men overpowered the sole officer in the office.
Officially, the PSNI would only say it was still investigating the incident and did not know if anything had been removed in the raid. Police sources, however, said a number of files were removed over a 30-minute period.
The Special Branch is the lead unit in gathering and disseminating intelligence on paramilitaries and any information contained in one of its offices, let alone its Belfast regional headquarters, would be considered sensitive.
The office is not easily located or accessed. The apparent ease and familiarity which the three men, at least one of whom had an English accent, displayed has led nationalist and unionist politicians to speculate that elements of either the British army or the intelligence services were involved.
Mr Alban Maginness, the SDLP assemblyman for north Belfast, said: "It is a Watergate-type of event and certainly raises all sorts of highly embarrassing questions for the security forces."
There are a number of closed-circuit television cameras and code-locked doors between the police station entrance and the office.
Mr Maginness said that with "all sorts of sophisticated codes and things like that to break through, it's just incredible. In circumstances like this one has to suspect the involvement of another security agency.
"What were they looking for, what did they take, how were they able to do all this and how were they able to escape?"
The break-in has been likened to a 1990 fire which destroyed files of the Stevens investigation into collusion between security forces and loyalist paramilitaries. It has since been claimed that this fire was started following a burglary by members of the army.
It is understood that a detective chief superintendent from outside the Special Branch is heading the investigation, which yesterday saw all of Castlereagh station closed down and searched.
The Special Branch office itself was sealed for forensic examination.
A spokesman for the Police Ombudsman said that while there were circumstances in which her office could begin an investigation into the affair it had no plans to do so at present."We are watching to see how it develops," he said.
In a statement, the Policing Board said the break-in was a "very serious incident" about which it was being kept fully informed.
It is understood the chairman and vice-chairman of the board were briefed by the Chief Constable, but a spokesman said that until more became known the board would not comment further.