The IRA is continuing to operate surveillance inside the Northern Ireland Office, security sources believe.

Today's Times quotes a security official as saying: "The worst case scenario right now is that there is still somebody inside there."

The paper also reports that the Royal Ulster Constabulary knew that the IRA was training Colombian guerrillas up to two years before three republicans were arrested in Colombia.

John Reid, the Northern Ireland secretary, has confirmed that security officials will conduct an "authoritative review" of procedures to establish how 1000 sensitive documents were stolen from government offices and passed to Sinn Fein.

Taxpayers face a £90 million bill to relocate hundreds of police and prison officers after their names and addresses were obtained by republicans.