The Police Ombudsman is investigating a claim that a break-in at the headquarters of the Police Service of Northern Ireland was allowed to happen to protect a high-level IRA agent.
Castlereagh police station in Belfast was burgled on St Patrick's Day 2002.
Intruders escaped with records on police officers and their agents inside paramilitary groups.
A former police officer has alleged that a "deliberate decision to allow the theft" had been made.
DUP MP Sammy Wilson said the claim by the former police officer needed to be properly investigated.
Mr Wilson, who was a member of the Policing Board at the time of the break-in, said there were serious questions about how top-secret intelligence documents were stolen from the police station.
"At the time we wondered how it was so easy for people to gain access to what was supposed to be a very secure station," he added.
"I don't know, is this republican propaganda to try and once again throw a bad light on the police or was it part of a deal to cover up republican collusion with the police?"
Millions of pounds were spent re-housing officers and others whose security was compromised by the theft.
Responsibility for the break-in was denied by the IRA at the time.
Security journalist Brian Rowan told BBC Radio Ulster's Stephen Nolan Show he had been informed of the complaint to the Police Ombudsman by solicitor Kevin Winters, who is representing the officer.
Mr Winters told Mr Rowan: "If the allegations are sustained, it points to a high level of republican and security force collusion and evidence of serious criminality.
"[It] begs the question: why was it allowed to happen, and what was the endgame in facilitating this operation?"
A spokesman for the Police Ombudsman said: "We can confirm that we have received a referral from the chief constable relating to an allegation from a former police officer that the break-in at the Castlereagh police station was allowed to take place.
"We have written to the solicitors concerned to ask if their client is willing to assist in our investigation and are currently awaiting a response."
Mr Winters has said his client is prepared to meet Police Ombudsman investigators.