BELFAST -- Sinn Fein, the IRA's political wing, and Britain on Friday staged their first formal talks in more than 70 years and agreed to continue the dialogue at a second meeting in 10 days.


After the three-hour talks, held exactly 100 days after the Irish Republican Army declared a ceasefire in Northern Ireland, Sinn Fein delegation chief Martin McGuinness said, "This is an historic opportunity that needs to be built upon. We've told the representatives of the British government it is now time to liberate the oppressed and the oppressor."


But Britain warned that the IRA's willingness to give up its arms was the key to Sinn Fein's entry into all-party talks on the future of the province.


Britain's Michael Ancram, minister for political affairs in Northern Ireland, said the disposal of the IRA's arms "has to be satisfactorily resolved during the course of this process. Their continued retention will constitute a barrier to other political parties, as well as to the government itself, in joining with Sinn Fein in substantive political negotiations."


He said the breakthrough talks had been "businesslike and constructive." The talks lasted an hour more than scheduled.


"I think many people realize it could have started much earlier if violence had ended much earlier. But it is a step forward, and a very important step forward," Ancram said.


Sinn Fein's delegation agreed to return for further talks Dec. 19 at Stormont Castle, a symbol of the Protestant majority's ascendancy.


McGuinness, imprisoned in Ireland in the 1970s, at the height of the Northern Ireland conflict, was upbeat and smiling following the talks, which could pave the way to peace after a 25-year conflict costing more than 3,000 lives.


The five-strong delegation, including convicted London bomber Gerry Kelly, called for an end to British military operations in the province and a release of IRA prisoners. Sinn Fein's ultimate aim is the unification of Ireland.


The group has objected to British suggestions that a referendum on the future of the province after all-party talks would concern the people of British-ruled Northern Ireland alone, and not the Irish Republic as well.


Sinn Fein said the British government's commitment to uphold a Unionist veto for the Protestant majority was an attempt to predetermine the outcome of all-party talks.


Britain said its fundamental approach was based on the right of self-determination and democratic consent, and that a a majority in Northern Ireland want to stay part of the United Kingdom.


But it said it was prepared to hold talks "in ways that compromise no position or principle, nor prejudice the future for any section of the people of Ireland, north and south, whatever their tradition."


British Prime Minister John Major, architect of the Anglo-Irish peace plan that has given Northern Ireland its best chance of peace in a generation, warned against overoptimism.


"I think one ought not to pin too much on today. This will be the first of a whole series of talks," he said at a European Union summit in Essen, Germany.