Catholic militants fought with police, torched trucks and tossed fire bombs today, protesting hard-line Protestant parades across Northern Ireland.

Scuffles left dozens of officers and demonstrators injured in Belfast before culminating in protests in Londonderry, where Protestants celebrated the city's 1689 defense from a besieging Catholic army. Groups traditionally start marching in other towns before gathering here for the main parade.

Suspected Irish Republican Army members hijacked and burned four trucks and vans on Londonderry's Catholic west side, while more than 10,000 Protestant members of the Apprentice Boys fraternal group paraded through the city center nearby.

Catholic men and youths hurled stones, bottles and 130 gasoline bombs at the lines of heavily protected riot police, who ensured there were no direct Protestant-Catholic clashes in Northern Ireland's second-largest city.

The violence coincided with the 30th anniversary of the deployment of British soldiers as peacekeepers in Northern Ireland. The forces were sent to the British province after police clashes with Catholics over the annual Apprentice Boys parade in Londonderry.

The Apprentice Boys are named in honor of 13 Protestant teenagers--apprentice workers in Londonderry industries--who bolted the city gates in the face of the approaching Catholic king, James II, in the late 17th century.

In Belfast, riot squads dragged more than 100 sit-down protesters off one disputed street, clearing the way for about 40 Protestant marchers. Police said 19 officers were injured.