Belfast - Police in Northern Ireland said Tuesday that 12 of their officers were injured during riots in the wake of sectarian parades in the province.

The Catholic pro-independence Sinn Fein party has blamed a dissident Republic group, the Real IRA, for the trouble in what was the worst night of violence Belfast has seen for years.

The Real IRA is an offshoot of the formerly-terrorist Irish Republican Army (IRA).

"This evening's actions expose very clearly the anti-peace process and sectarian agenda which feeds these factions."

It has nothing whatever to do with Irish republicanism," Sinn Fein member of the Northern Ireland Assembly Gerry Kelly told the Dublin daily newspaper The Irish Times.

The Police Service of Northern Ireland (PSNI) said the most serious violence was in the Ardoyne area of north Belfast where nine officers were hurt. One shot is reported to have been fired and petrol bombs, fireworks and other missiles were thrown at police lines.

Police used water cannon and fired 18 non-lethal projectile rounds at their attackers. The area was reported calm by 2 am Tuesday morning.

July 12 parades were being held at 18 venues across Northern Ireland with marches taking place on Monday 13 because the commemoration fell on a Sunday.

Hundreds of bands and members of hundreds of orange lodges took part in the parades which celebrate the victory of Protestant King William of Orange over the Catholic King James at the Battle of the Boyne in 1690.

Trouble was also reported in Rasharkin, Co Antrim, where three police officers were injured and in Derry and Armagh.

Police assistant chief constable Alistair Finlay said: "They displayed the worst possible face of Northern Ireland - a face of bigotry, sectarianism and intolerance that is not representative of the vast majority of people who have moved on and embraced a peaceful future."

Power-sharing was restored to Northern Ireland in May 2007 after a series of agreements brought the region's bloody 30-year conflict between Catholics and Protestants to an end. (dpa)