Several demonstrations have taken place in Northern Ireland in protest at the recent deadly attacks on security forces in the province.Dissident Republican groups have said they were behind the killing of a policeman on Monday night and two soldiers over the weekend. Leaders of all political parties have condemned the attacks, vowing they will not derail the province’s peace process. The British Prime Minister Gordon Bown told parliament: “In Northern Ireland today we are seeing a degree of unity amongst the political parties that some people thought that they would never see in their lifetimes.” Two men are still being questioned by detectives investigating the killing of the policeman in the town of Craigavon. The splinter group the Continuity IRA says it was behind the death. The officer was gunned down as he responded to an emergency call. Another dissident group, the Real IRA, has claimed responsibility for the killing of the two soldiers at an army base in Antrim.