Seven men appeared in court in Northern Ireland on Monday charged with "terrorist offences" including plans to target police officers and judges.

The seven were ordered to remain in detention following an investigation into republican militants opposed to the peace process in the province.

A small explosion hit Northern Ireland's capital Belfast Friday after authorities received a telephone bomb warning, police said. There were no immediate reports of injuries.

The incident happened in the city's central Cathedral Quarter area near many restaurants and bars on one of the busiest shopping nights before Christmas.

Dozens of police officers were injured during riots by pro-British Protestants in Belfast, in what Northern Ireland's police chief condemned on Saturday as "mindless anarchy".

A total of 56 officers were hurt, four requiring hospital treatment, when they were attacked with bricks, bottles and paving stones from the street on Friday night, police said.

Dozens of police were injured in Belfast on Friday evening after clashes broke out during protests against a rally marking the introduction of imprisonment without trial in Northern Ireland.

Some 26 police officers were injured, five requiring hospital treatment, when they were attacked with bricks, bottles and other missiles by crowds in the city center, police said.

Northern Ireland's First Minister Peter Robinson on Sunday called for peace as a police officer was hurt in the third night of disorder in Belfast.

"It's very important that this violence stops," said Robinson.

Seven police officers were injured in Belfast after being attacked with petrol bombs in a second night of violence by Protestant rioters in the Northern Irish capital, a spokeswoman said Sunday.

Bricks, bottles, furniture and other missiles were also hurled on Saturday night by hooded youths, some with British flags covering their faces.

Police in Northern Ireland fired plastic bullets and water cannon on Friday as pro-British loyalists furious over restrictions on flying the British flag torched a bus and hurled petrol bombs at officers.

Violence also flared in towns outside the capital Belfast as loyalists -- the Protestant community's working-class hardcore -- blocked roads around the province to express their anger.

Police in Northern Ireland arrested a 38-year-old man on suspicion of attempted murder on Saturday after reports of shots fired at officers during fresh protests in Belfast.

The unrest followed a largely peaceful demonstration by more than 1,000 people against Belfast city council's December 3 decision to limit the days it flies the British flag each year, a ruling which has sparked weeks of street violence.

Police in Northern Ireland arrested two men on Friday in connection with the murder of a prison officer who was shot dead as he drove along a motorway to work, police said.

The men aged 31 and 44 were arrested in the Lurgan area of County Armagh, southwest of Belfast, in the early hours of Friday and are being questioned, the Police Service of Northern Ireland said in a statement.

Rioters threw fireworks and other missiles at Northern Ireland police during the third night of sectarian disorder in north Belfast on Tuesday, police said.

One officer sustained a hand injury and a water cannon was moved into the Denmark Street area, although not used, as a group of around 200 people gathered at 10:00 pm (21:00 GMT).