Irish Republican Army supporters clashed with police on Monday and forced Olympic torch organizers to divert the route of their relay, marring what had been a jubilant day's procession through a sun-soaked Northern Ireland.

Police said at least one protester was arrested after members of a 200-strong group broke through police lines as the torch passed the city hall building in Londonderry, Northern Ireland's second-largest city. Londonderry is a power base for several small IRA factions still plotting to wreck the peace process.

The protesters made clear they were seeking to confront police, not the Olympic torch itself. Many carried placards denouncing the police, who have mounted raids in Irish republican parts of the city ahead of the torch's visit.

Officers surrounding the torchbearer, 58-year-old Isobel Coote, quickly changed course and escorted her down a side street where she resumed her journey to the city's new pedestrian Peace Bridge. It spans the River Foyle, which divides Londonderry into a predominantly British Protestant east side and an Irish Catholic west.

Earlier, British Army experts dealt with a suspected bomb left near a Catholic high school but declared it a hoax device.