Police blamed the IRA for firebombs that caused blazes at three London stores Thursday in the first guerrilla attack on the British mainland since a peace drive in Northern Ireland was launched last month.

No one was hurt in the fires on Oxford Street, London's principal shopping street. The area was cordoned off after the fires broke out before dawn but was reopened about three hours later."Anti-terrorist branch officers have confirmed that the fires this morning were caused by devices which are clearly attributed to the provisional IRA," a police spokeswoman said.

There were no immediate claims of responsibility. But the Irish Republican Army has firebombed shops in London in the past as part of its guerrilla campaign to end British rule in Northern Ireland.

Thursday's attacks were the first in London since British and Irish leaders signed a peace declaration Dec. 15 aimed at persuading the IRA to lay down its arms and join talks on the area's political future.

The peace initiative has bogged down amid IRA demands for clarification and the refusal of the Dublin and London governments to explain details until violence ends.