LEEDS CASTLE, England (AFP) - British Prime Minister Tony Blair said the "moment of decision" had come for Northern Ireland's Catholic and Protestant leaders to break two years of deadlock and secure a lasting peace.

"We've been through these issues many times. They haven't changed. But now it's time we got to decide it," Blair said after greeting Irish Prime Minister Bertie Ahern at Leeds Castle, the venue for the all-party talks in southeast England.

"We can't go out of this and have another set of elongated negotiations," said Blair, renewing his warning that after three major pushes in two years the leaders may not repeat the effort should they fail here.

Blair and Ahern are hosting the all-party talks aimed at restoring the power-sharing government set up by the Good Friday agreement of 1998, which was suspended in October 2002 amid allegations of spying by the Catholic paramilitary Irish Republican Army (IRA).

The end of IRA violence and its total disarmament are the keystone to any deal with the Protestant camp, especially the hardline Democratic Unionist Party which has refused to sit down at the table with the IRA's political wing, Sinn Fein.

But now both are Northern Ireland's largest elected parties, and keen to exercise their newfound power in a restored government -- even if this means negotiation with arch-rivals.

Ahern, speaking alongside Blair, said: "We want to see an end to paramilitarism through decomissioning, and the cessation of all paramilitary activity."

"I do hope we leave Leeds Castle with a success, not a failure. I hope with finality, and not just a parking spot on the way", he said, adding: "It's an issue of whether the people have the will to conclude the agreement."

The parties, which also include the Ulster Unionist Party and nationalist Social Democratic and Labour Party, met Thursday with Irish Foreign Minister Brian Cowen and Paul Murphy, Britain's secretary of state for Northern Ireland.

Blair and Ahern were expected to meet the parties separately later in the day.