Heralding a new era of cooperation in a land torn by competing allegiances and religion, politicians reached a comprehensive accord today on governing British-ruled Northern Ireland.

The breakthrough - the biggest political development since conflict engulfed Northern Ireland in 1969 - capped a weeklong negotiating marathon driven by the American talks chairman, George Mitchell, and the prime ministers of Britain and Ireland, Tony Blair and Bertie Ahern.The announcement came on Good Friday, more than 17 hours past a midnight deadline set by Mitchell to force the pace in the negotiations, which began 22 months ago after years of preparation.

The British government said leaders of the eight participating parties would not be required to sign the accord.

The agreement, subject to approval by voters in both parts of Ireland next month, offers at least a hope of ending a conflict that has claimed more than 3,400 lives in Northern Ireland, the Irish Republic and Britain.

The key points of the accord would mean substantial changes to relations between Britain and the Republic of Ireland and especially to Northern Ireland, where the two nations' interests and identities have overlapped for decades.

Protestants and Catholics will be expected to govern their land of 1.6 million people together in a 108-member assembly. That would end 26 years of "direct rule" from London, instituted after the British abolished a Protestant-dominated parliament that had governed Northern Ireland since its creation in 1921.

Critically, the new Belfast assembly will be expected to cooperate formally with the Irish Republic in a north-south council of lawmakers. This measure is considered essential to win support from the north's Catholics, who generally favor the unification of Ireland.

But the Protestant bloc appeared to have won a substantial concession, because the Belfast assembly will have the right to approve decisions taken by its members in the cross-border council. Catholics had pushed for the council to wield independent powers.

The IRA-allied Sinn Fein party - brought into the talks eight months ago following an Irish Republican Army truce - appears to have accepted the agreement, which stops so far short of its traditional goal of uniting Ireland.

Before the accord was announced, however, Sinn Fein leader Gerry Adams said he would need the formal approval of grass-roots members of the party.

The Ulster Unionists, Northern Ireland's main pro-British Protestant party, also will face stern opposition from Protestants who suspect that any settlement will concede too much to those seeking Irish unification.

The accord will have to be approved by majority votes next month in both Northern Ireland and the Irish Republic, where voters also will be asked to approve the softening of their constitution's territorial claim to Northern Ireland.

The agreement specified that the amended claim would emphasize the right of people in either part of Ireland to consider themselves Irish - but that Ireland would be united only when a clear majority of people in Northern Ireland wants it to happen.

The agreement does not mean a certain end to shootings and bombings in Northern Ireland, since dissidents have already broken away from both the IRA and those pro-British paramilitary groups observing truces as a condition for participating in the talks.

President Clinton was up in the early hours Friday keeping tabs on the talks, White House spokesman Mike McCurry said.