LONDON -- Britain on Thursday invited the political wing of its archenemy the IRA to unprecedented talks next week to try to cement Northern Ireland's fragile peace.


The government, pursuing a year-old peace plan, has set aside its refusal to deal with the people it once called "terrorist apologists," and asked Sinn Fein to meet senior civil servants Dec. 7 in Belfast.


Sinn Fein, which Wednesday accused Britain of dragging its feet after London said talks were unlikely before the end of the month, said it would reply quickly to the early offer.


"The opportunity to realize a lasting peace, which will benefit all of the people of Ireland, has never been greater," Sinn Fein's leader, Gerry Adams, said in a statement issued in Belfast.


The exploratory talks, leading later to a place for Sinn Fein at all-party discussions on Northern Ireland's future, are a reward for the Sept. 1 cease-fire the Irish Republican Army has declared in its 25-year war to end British rule.


Separate British talks with the IRA's armed Protestant foes, who responded with a cease-fire of their own in October, are also likely to take place.


Fighting by guerrilla groups and security forces has cost more than 3,000 lives, many of them civilians, since 1969.


"The exploratory talks will be a vital step in the process of consolidating a lasting peace in Northern Ireland," an aide to Prime Minister John Major told Sinn Fein in the invitation.


Major's office said the decision to hold "talks about talks" was possible only because the government had been able to make a working assumption that the truce was permanent.


"The opening and continuation of this dialogue of course depend on Sinn Fein's continued commitment to exclusively peaceful methods and the democratic process," it said.


Major's office left the door open for Sinn Fein also to attend, semiofficially, a conference in Belfast on Dec. 13 and 14 aimed at cashing in on the "peace dividend" by attracting investment to Northern Ireland.


Government sources said Major had been worried Sinn Fein's anger at intially being excluded could mar the event, to be attended by U.S. Commerce Secretary Ron Brown.


In Washington, President Bill Clinton welcomed the announcement of talks and named Senator George Mitchell as a special adviser for economic initiatives in Ireland. He said the retiring Senate Democratic leader would spur U.S. efforts to promote peace there.