Northern Ireland clashes over the weekend have resulted in 56 police officers and two civilians being injured as a result of battling factions within the nation's Catholic and Protestant communities.
Many of the injuries were minor, but four officers were taken to hospital after the clashes late on Friday, during which police fired plastic bullets and water cannons after being pelted with missiles for a second successive night, Reuters reported.
Belfast remains divided between pro-British Protestants and Catholics who generally favor unification with Ireland, despite a 1998 peace and power-sharing deal that put an end to the worst of the "troubles" in the British province.
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Protestants tried to block a march on Friday evening along the city's main thoroughfare, Royal Avenue, by the nationalist side of the community and when police moved in to clear them, they threw bricks, bottles and fireworks.
Burnt-out cars and rubble littered the city centre and shop fronts were damaged. Police said seven people were arrested.
"It was sheer thuggery," said Assistant Chief Constable George Hamilton, who commanded Friday night's police operation.
"There were all sorts of weapons and equipment being used against the police including scaffolding and masonry. People were pulling up the paving stones from the busiest shopping precinct in Belfast."
The Catholic parade, marking the anniversary of the 1971 introduction of internment without trial by British authorities, eventually had to pass along a different route.
Eight were hurt on Thursday night when a crowd at a bonfire to mark the anniversary in a Catholic-dominated part of Belfast threw paint bombs, bottles and masonry at police.
Forty-two years ago, soldiers swept into Catholic districts and arrested more than 340 people as the British government sought to halt growing Irish Republican Army (IRA) violence aimed at extinguishing rule from London.
"Last night's violence and attacks on police officers were shameful," Britain's minister for Northern Ireland, Theresa Villiers, said in a statement. "Disorder on the streets is a hugely regrettable step backwards."
Since the late 1960, more than 36,000 individuals have been injured while more than 3,600 people have died as a result of sectarian conflict in Northern Ireland, of which more than 1,000 were British security force members.
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