More than 30 police officers were injured and 11 people arrested during overnight violence around traditional Orange Day parades in Northern Ireland, authorities said on Saturday.
Thousands of pro-British Protestants march every summer in the British province, a regular flashpoint for sectarian violence as Catholics, many of whom favor unification with Ireland, see the parades as a provocation.
Violence between the two religious groups still sometimes flares since a peace deal was signed in 1998, which largely ended three decades of trouble. Much of Belfast remains divided along religious and nationalist lines.
A total 32 police were injured in what Chief Constable Matt Baggott described as "shocking and disgraceful" violence, including head, eye and leg wounds. Another 400 reinforcements were being brought in from Britain.