The Sinn Fein chairman, Mr Mitchel McLaughlin, has called on the two governments to avert the "course of collapse" of the power-sharing Executive.
Describing the current situation as the "most serious crisis yet in the peace process", Mr McLaughlin said the First Minister, Mr David Trimble, was attempting to get the North's institutions suspended and to blame republicans for it.
The British government, which had a duty to protect the integrity of the Belfast Agreement, had so far failed to do so, the Sinn Fein chairman said.
"It is for the British government to use their power to force David Trimble to change course. Otherwise, the result is clear to see. David Trimble must be moved from his current strategy on to one which is within the terms of the Good Friday agreement. Only the governments, but particularly the British government, have the power to achieve this," Mr McLaughlin said.
Sinn Fein is considering a legal challenge to the ban which Mr Trimble has imposed on the party's two Ministers, Mr Martin McGuinness and Ms Bairbre de Brun, to prevent them from attending North-South Ministerial Council meetings.
Mr McLaughlin also accused the UUP leader of attempting to scupper police reform and usurping the independence of Gen de Chastelain's Independent International Commission on Decommissioning.
Mr Trimble's party colleague, the Environment Minister, Mr Sam Foster, last night rejected Sinn Fein's accusations and denied his party was out to wreck the North's institutions.
"David Trimble remains pro-agreement. Does anyone believe David Trimble would have put up with so much political pressure and personal abuse for something in which he didn't believe? Does anyone actually believe that David Trimble would welcome a return to direct rule and the accompanying risk of joint sovereignty through an Anglo-Irish Agreement Mark Two?"
Meanwhile, Sinn Fein has instituted legal proceedings against the Northern Secretary, Mr Peter Mandelson, over his decision to issue regulations on the flying of flags from government buildings, including the two Sinn Fein Ministers' departmental offices, on 17 designated days of the year.
The party's equality spokesman, Mr Conor Murphy, confirmed Sinn Fein had applied for a judicial review of Mr Mandelson's regulations, to take place in Belfast today or tomorrow, on the grounds that the Northern Secretary had exceeded his powers.