The prime minister has urged the people of Northern Ireland to "choose the future, not the past" in Wednesday's election.

Speaking on Monday, Tony Blair accepted that the final choice rested with the Ulster electorate.

"This election will be a very big moment for people in Northern Ireland and we are now at a point in the politics of Northern Ireland where I can't make any more decisions, I can't renegotiate agreements, I can't rewrite those things that have already been agreed," he told journalists in London.

"The decision is now for people of Northern Ireland and they're going to have to decide, in a fundamental way, whether Northern Ireland today is a better place than it was six, seven, 10 years ago and if it is, they're going to have to come and vote for it."

Blair added that making the agreement work was "something the politicians can't do on their own".

"The people have got to play their part now, and I just hope people bear in mind whatever frustrations and difficulties there are that Northern Ireland, actually as everybody really knows, is in far better shape than it was a decade ago," he said.

"That is only because people had the courage to come together and to make an agreement and that's what I say to people. And if people vote on election day in Northern Ireland they make a choice; if they don't vote, if they stay at home, they make a choice.

"And I hope people choose the future, not the past, but that's a decision for them."

There have been fears of a low turnout following the last row to hit the Good Friday agreement.

Ulster Unionist leader David Trimble refused to complete moves towards a pre-election deal, claiming that the IRA had not been sufficiently transparent in its last act of decommissioning.

Concerns have also been raised that anti-agreement parties such as the Democratic Unionist Party could do well, leading to difficulties in the establishment of a new power-sharing executive.

Speaking earlier in the day, Northern Ireland secretary Paul Murphy urged Ulster people to vote on Wednesday.

"The main thing is that people see these elections and the restoration of government in Northern Ireland as progress, however difficult it might be, rather than go backwards," he said.

"The first thing we want is everybody who is eligible to take part in the election and after that we will see what emerges.

"We will look to what is common to the parties, devolution being restored and we will work towards that aim."

A total of 256 candidates are standing, a smaller number than in the first poll in 1998.