Mr Tony Blair and Mr David Trimble had a brief discussion on the proposal to invite Amnesty International and Human Rights Watch to monitor alleged paramilitary breaches of the cease-fires during a 45-minute meeting in London last night.
After the meeting - during which the Prime Minister and First Minister designate reviewed developments in the peace process "in the round" - a Number 10 spokesman said Mr Blair would look at the proposal constructively.
Earlier, during Prime Minister's Questions in the Commons, the Labour MP, Mr Harry Barnes, suggested the plan - which originated in an Observer editorial - could force paramilitary groups "to back off". Quoting Amnesty's initial favourable response, Mr Barnes asked Mr Blair to give the idea of a ceasefire monitoring group "good passage".
Number 10 said the development of the idea would now be a matter for Northern Ireland Office ministers in consultation with the political parties.
Mr Trimble said he had "a good meeting" with the Prime Minister, during which they discussed a number of issues - including the Drumcree situation, the impasse on decommissioning and the creation of the power-sharing executive.
During question time, Mr Blair again dismissed Tory calls for a halt to prisoner releases and he rejected a suggestion from Mr William Ross that Sinn Fein had told him and the Taoiseach, Mr Ahern, "that it could not bring about or force the IRA to decommission weapons".
Mr Blair told the East Londonderry MP: "No. In the agreement it is very clearly set out that decommissioning is part of the agreement and that they are expected to do what they can to bring decommissioning about, just as every other party is. They are bound by that agreement." The Department of Foreign Affairs said it had no formal notice of Amnesty's intentions, but a spokesman voiced concern that the group's initiative "might elevate the perpetrators of punishment beatings to a status they didn't deserve".