SINN FEIN accused Mr John Major of "dumping" the twin track process by suggesting that an election to a new assembly in the North could be the way forward.
The party president, Mr Gerry Adams, had reacted favourably to the Mitchell report earlier yesterday. However, his upbeat note changed after the Prime Minister's comments in the House of Commons later.
Mr Adams accused Mr Major of bad faith. "The Mitchell report was the conclusion of one track of the twin track approach which was set up to move us all into all party talks by the end of February, he said.
"In his reaction to this, John Major has effectively dumped the Twin Track process. Hem is quite clearly acting in bad faith by swapping one precondition to all party talks for another. Mr Major has now adopted an entirely unionist agenda in an attempt to buy unionist votes in Westminster."
Earlier, Mr Adams had said that the Mitchell report vindicated Sinn Fein's position that the decommissioning of paramilitary weapons before all party talks was impractical.
"I am glad that the international body has accepted the argument that this is an unreasonable demand and that all issues should be dealt with in open, democratic negotiations," he said.
The report provided a basis for "moving forward so that all matters can be settled to the satisfaction of all sides," he added. He accused the British Government of already "wasting" 17 months since the IRA ceasefire.
"There is no justification for further stalling. The onus is very clearly on John Major. He should now act by immediately commencing all party talks," Mr Adams said.
By contrast, Republican Sinn Fein and the Irish Republican Socialist Party criticised the Mitchell report. Mr Ruairi Og O Bradaigh of Republican Sinn Fein predicted that it would lead to a "new Stormont".
He said "The report recommends a commitment to acceptance of the outcome of talks in which the unionists will have majority representation. It recommends an elective process confined to the Six Counties which can lead only to a new Stormont. Republican Sinn Fe in is committed to democracy on a 32 County basis Ireland taken as a single unit. We note that the heavily armed British forces of occupation were not included in the report."
The Irish Republican Socialist Party, the political wing of the INLA said that the report contained nothing that could break the logjam. A party ardchomhairle member, Mr Kevin Quillan, said that it did not move the peace process forward by "one iota" and indeed had added "new preconditions" by committing republicans to accepting the outcome of all party talks.
He said that republicans had offered I 8 months of peace, yet the British government and the unionists had not "moved an inch".