THE RETURN of Sinn Fein to the cross-party talks on Ulster offers "the best prospect for peace" in Ireland, Tony Blair will tell Gerry Adams today when the two men meet at 10 Downing Street.

Sinn Fein could have rejoined the talks last Monday, following the three-week suspension imposed for a recent surge in IRA violence, but representatives are seeking to lay down demands for progress in the negotiations, including a long-term call for the release of prisoners, including Roisin McAliskey, whose extradition to Germany was halted earlier this week on health grounds.

The Prime Minister's official spokesman said: "[Mr Blair's] message will be the same as it has been throughout - that we have got the best prospect for peace, and that it is worth taking risks for peace."

Mr Blair will emphasise that the talks process now has to be accelerated to enable Dublin and London to meet their target of a referendum on both sides of the border in May.

Sinn Fein's absence from the negotiating table would, however, blow a hole in the process and Downing Street officials were holding out strong hopes that Sinn Fein president Mr Adams and his colleagues will return after today's talks.

The officials said Mr Adams may have warned Dublin against dropping its historic claim to the north, as part of the peace package, but they pointed out that other remarks were more helpful. These include the acknowledgement that these negotiations cannot deliver a united Ireland at this stage.

John Hume, leader of the nationalist SDLP, last night reinforced the pressure for Sinn Fein to return after meeting Mr Blair at Downing Street. Mr Hume said the talks were entering a "crucial" phase.

"We want to see them where the rest of us are - all round the table," Mr Hume said. "We hope they will come back to the table very soon and get down with the rest of us in this very crucial period on the road to an agreement."

Sinn Fein leaders have said they will only decide whether to rejoin the peace process once they have had a face- to-face meeting with the Prime Minister, but it is widely expected that they will be back at the talks at Stormont, Belfast, on 23 March.