Pro-British militant groups are instigating riots that have rocked the Northern Irish capital Belfast in the past month, a police officers' representative said on Sunday, Jan 7 as officers came under attack again, Reuters reported.

The violence stems from protests over the removal of the British flag over Belfast City Hall. It has been among the province's worst since a 1998 peace accord ended 30 years of conflict in which Catholic nationalists seeking union with Ireland fought British forces and mainly Protestant loyalists.

Fireworks, bottles and bricks were flung at officers for a fourth successive night on Sunday although a police spokeswoman said the trouble was not on the scale of the previous night, when police came under attack with petrol bombs and gunfire.

By Sunday, 70 people had been arrested, including a 38-year-old man detained on Saturday on suspicion of attempted murder over the shooting.

Both the UVF (Ulster Volunteer Force) and Northern Ireland's other main loyalist militant group, the Ulster Freedom Fighters, ceased hostilities in 2007 and decommissioned their stocks of weapons following the signing of the peace deal.