The British government has failed to deal adequately with recent loyalist violence, Sinn Féin president Mr Gerry Adams has said.
Speaking to reporters outside Downing Street before a meeting with the British Prime Minister Mr Tony Blair, Mr Adams said the Blair administration had not "got it right" in dealing with the loyalist "killing campaign".
"The British prime minister has to face up to the reality that the threat to the peace process comes from within loyalism . . . and agencies of the British state that have run loyalist death squads," he said.
Sinn Féin will later occupy offices in Westminster after a ban preventing them from using facilities available to MPs was lifted in December.
The party was barred from using Westminster facilities as its MPs refused to pledge allegiance to the British queen.