BELFAST, NOV. 9 -- The Provisional Irish Republican Army admitted today that it planted the bomb that killed 11 persons and injured 63 during a solemn veterans' day ceremony yesterday, but it said that civilians were killed only because the explosion had been triggered prematurely by a British Army electronic bomb-search device.

The British government denied that the Army set off the explosion in Enniskillen, southwest of here, and the Royal Ulster Constabulary said that no such equipment was in use at the time.

Minister for Northern Ireland Tom King called the IRA claim "disgraceful," "untrue" and "a pathetic attempt to transfer blame."

The bomb's location, in a community center building next to a town square where spectators gathered to honor British war dead, guaranteed that civilians would be victims, King said.

Gerry Adams, the president of the IRA's Sinn Fein political wing, clearly troubled by widespread public outrage over one of the deadliest attacks in the IRA's history, issued an unusual statement expressing "regret" over the bombing.

In recent years, the IRA has sought to avoid killing civilians because of the negative political impact of such attacks. In yesterday's bombing, however, the dead were civilians, although one man belonged to the police reserves. Seven of the dead were retired persons more than 60 years old, and one was a 20-year-old student nurse.

"I do not try to justify yesterday's bombing. I regret very much that it happened," said Adams, a member of the British Parliament. "On behalf of the republican people, I extend sympathy and condolences to the families and friends of those killed and injured yesterday."

The IRA guerrillas, in a statement issued in Dublin, regretted the loss of life but did not apologize. The statement said the bomb had been intended for soldiers or police.

The IRA statement said that its bombs had been detonated in the past by British Army scanning devices, but that it had believed the problem was "overcome."

The IRA statement came closest to offering an apology when it concluded, "In the present climate, nothing we can say in explanation will be given the attention or the truth it deserves, nor will it compensate the families of the injured or the bereaved."

In response, British Minister King said, "Anybody who knew anything about that parade {at the ceremonies} knew that the spectators would be standing by that building."

The IRA probably planted yesterday's 30-pound bomb as a show of strength after a string of embarrassments this year, security officials and private observers said.

In May, British commandos killed eight IRA gunmen in an ambush. Ten days ago, French authorities confiscated a ship carrying 150 tons of arms that apparently were destined for the IRA.

BBC television reported this evening that the U.S. government tipped off the French after the ship was loaded off the Libyan coast. The United States had been watching Libya because of tensions in the Persian Gulf, the BBC said.

"In the wake of a number of setbacks, the IRA without a doubt would be very anxious to show that it still has teeth, that it's still in business," said Eamonn Mallie, a Belfast radio reporter who coauthored a recent book about the IRA. In a telephone interview, he said that the attack was disastrous for the IRA's reputation because of the civilian casualties.

"In politics, you can shoot yourself in the foot. The IRA has shot itself in the head," Mallie said.

The IRA is fighting to unify Northern Ireland -- which is part of Britain and is predominantly Protestant -- with the mostly Roman Catholic Republic of Ireland on the southern part of this island.

The bombing led to new appeals from Protestant politicians here for tougher measures against the IRA and especially for preventive detention of suspected terrorists. King said that that measure was under review.

The attack also increased political pressure on Irish Prime Minister Charles Haughey to implement an agreement with Britain to allow IRA terrorists to be extradited to Britain for trial. The accord is supposed to be enacted on Dec. 1, but Haughey has been seeking new concessions from London in return for adopting it.

The proposed extradition agreement was one of the results of the two-year-old Anglo-Irish accord, which gave Dublin a consultative role in major policy decisions affecting Northern Ireland.

Northern Irish Protestant leaders, who have strongly opposed the accord, said that the bombing showed that the agreement was useless. They charged that the attack demonstrated the accord had failed to improve security in Northern Ireland.

Protestant Leader Ian Paisley, clearly hinting that Protestant paramilitary groups should avenge the bombing, said, "We must seriously consider taking the law into our own hands."

The British government said that the bombing only showed more than ever that it was necessary for London and Dublin to cooperate in fighting the IRA.

In what police described as a retaliatory attack yesterday evening, five Roman Catholic men were wounded by gunmen.

A workman was shot dead by a gunman today in a Belfast housing development but the circumstances were unclear. In another development, a British Army squad defused a huge, 1,200-pound bomb found in a stolen van in downtown Belfast. Police said that bomb also was planted by the IRA.