Northern Ireland’s agreement on the devolution of policing and justice will unravel unless the Treasury agrees to more than £1bn ($1.5bn) in extra funds over the next three years, a leading member of the province’s majority party warned on Thursday.

Gregory Campbell, Democratic Unionist MP for East Londonderry, said the province’s power-sharing executive, which met for the first time in almost five months on Thursday, would not be able to fund an estimated £300m in continuing policing costs. These relate to a new police training college, a significant overhaul of the service’s IT system, and compensation owed to officers who have had to move home because of threats from dissident republicans.