BELFAST, Northern Ireland (AP) _ A 23-year-old man was charged Monday with killing three young brothers in a firebombing that stunned Northern Ireland and prompted Protestant leaders to tone down efforts to hold a divisive march.

The suspect in the July 12 attack in Ballymoney, 40 miles northwest of Belfast, was not identified. He will appear in a Belfast court on Tuesday, police said, giving no other details.

Police investigating the slayings of the Quinn brothers _ Richard, 11, Mark, 10, and Jason 9 _ said the attack was linked to tensions caused by a violent standoff outside Portadown, 25 miles southwest of Belfast.

Protestant marchers faced off against armed authorities blocking them from parading down a largely Catholic road for nearly a week.

Stunned by the killings, some leaders of the Orange Order fraternal group that organized the march called for an end to the confrontation. The standoff quieted down and efforts to continue the march have now virtually ended.

Authorities say they believe the Quinn household _ located in a Protestant housing complex _ was targeted because the boys' Catholic mother lived there with her Protestant boyfriend.

In Londonderry, meanwhile, the British government opened an inquiry into the 1972 deaths of 13 protesters on ``Bloody Sunday,'' which provided a rallying point for the IRA's campaign against British rule. Protesters were killed after soldiers opened fire. An inquiry that followed found the shootings justified, angering many Catholics. Britain began the new investigation as a concession intended to promote the peace process.

In another development, a senior Sinn Fein leader said Monday that the punishment-style killing of a Belfast man Sunday was ``wrong,'' but he did not respond Monday to claims by the victim's mother that he was killed by the IRA.

``I don't know who carried out the attack, therefore I can't speculate about what happened,'' said Gerry Kelly, a member of Sinn Fein's negotiating team at the Northern Ireland peace talks.

Andy Kearney, 33, died Sunday morning after masked men broke into his apartment, dragged him outside the door, shot him in the legs and left him to bleed to death.