Sinn Féin leaders are to visit Downing Street today to discuss the latest proposals to return powersharing to Northern Ireland.
Mr Gerry Adams and Mr Martin McGuinness will meet Mr Tony Blair and are expected to raise their concerns about some aspects of the Irish and British proposal to revive devolution and secure IRA disarmament.
After talks yesterday with the Taoiseach, Mr Ahern, in Dublin yesterday, Mr Adams said: "There are issues of concern for Sinn Féin and we have made the point that viable proposals for forward movement must be firmly grounded in the Good Friday Agreement.
"I do believe if our concerns are adequately addressed, we could have the basis for a comprehensive agreement."
The governments' proposals also alarmed SDLP leader Mr Mark Durkan, who claimed they went too far towards the position of the Democratic Unionists.
The Foyle Assembly member told a debate at UCD last night that plans to replace the joint election of First and Deputy First Ministers in the Assembly with a block vote for the entire team of powersharing ministers were foolish.
"It means that DUP have a veto over any nationalist minister appointed to the executive," he claimed. "When the SDLP negotiated the Agreement, we ensured that no party could veto any other party's ministerial appointment.
"Now, the DUP can politically vet the lot. Nationalists won't have the last say on who they appoint as ministers. The DUP will," Mr Durkan said.
Sources claimed that the two governments have proposed a target date for the transfer of policing and justice powers from Westminster to Stormont within two years.