BELFAST (Reuters) - Protestant guerrillas threatened on Thursday to break their 1994 ceasefires if Britain responds to any collapse in Northern Ireland‘s peace deal by forcing new political structures on the province. The threat piled pressure on the British and Irish governments and politicians in the British province struggling to break a deadlock in implementing a year-old peace accord. Exposing another raw nerve, an innocent verdict in a trial of a Protestant man accused of killing Robert Hamill, a Roman Catholic, sparked calls from his family and pro-Irish nationalists for a public inquiry into his death. Relatives of 25-year-old Hamill, kicked to death by pro-British extremists in 1997, were represented by lawyer Rosemary Nelson, a champion of Catholic rights killed on March 15 by a car bomb planted by pro-British loyalist extremists. The British and Irish Prime Ministers, Tony Blair and Bertie Ahern, are expected in Belfast on Monday to try to get rival parties to end an impasse on disarmament which is blocking the implementation of new political structures. The Ulster Volunteer Force (UVF) and the Red Hand Commando (RHC) said in statements they would "retreat from all theories of process — peace or political" if Britain imposed the accord‘s political structures, which includes closer links with the Irish Republic, over the heads of Protestants. Britain has imposed the week up to Easter Sunday as the deadline for implementing the accord. The key problem faced by politicians now is that First Minister David Trimble, under heavy pressure from his Protestant community, refuses to let the Catholic Irish Republican Army‘s political wing Sinn Fein sit in a coalition cabinet until the IRA starts disarming. Bolstered by the fact that the peace deal stipulates no starting date for disarmament, Sinn Fein, the IRA‘s political wing, has said it cannot make the IRA hand over its guns.