In a strongly-worded newspaper article, he attacked the government's handling of the Northern Ireland peace process and its decision that the IRA ceasefire remains intact.

He said that the refusal by Prime Minister Tony Blari to halt paramilitary prisoner releases was "an outrage and a betrayal of the trust of the people of Northern Ireland".

He also said the ruling that the ceasefire was holding "quite simply flies in the face of the admitted facts and smells of fudge and sham."

The Conservatives have demanded a halt to prisoner releases as a sanction against the republican movement, amid growing anger over punishment beatings and IRA threats.

Listen to Robin Oakley's interview with William Hague in full

Mr Hague's comments are one of the strongest indications yet of a breakdown in the broad bipartisan agreement between Labour and the Tories over the direction of the peace process.

But they have been condemned by Labour and the Liberal Democrats who say the remarks will not assist the peace process.

William Hague has demanded an end to paramilitary prisoner releases

The Tory leader singled out Tony Blair in his attack, going so far as to raise the prime minister's integrity as an issue.

"The integrity of the peace process requires, and Tony Blair's own integrity demands, that he now steps in and demonstrates to the IRA that the agreement means what it says and he means what he says," he said.

The attack comes after Mr Blair indicated that he fully supported Northern Ireland Secretary Mo Mowlam's controversial verdict on the ceasefire.

'Tory sniping'

Dr Mowlam dismissed the Tory leaders intervention as "sniping at the sidelines" that would be unhelpful to the peace process.

Lembit Opik says Mr Hague is trying to making political capital

"That disappoints me because I believe bipartisanship is important to the process. They seem to be backing off from that," she said.

Lib Dem Northern Ireland spokesman Lembit Opik also attacked Mr Hague's remarks.

He accused the Tory leader of trying to make political capital out of the crisis in the peace process.

"There are no party political points to be gained by making it hard in Northern Ireland.

Lembit Opik MP, Liberal Democrat, Northern Ireland: "The Tories are taking a belligerent attitude"

"So William Hague really needs to explain is he still supportive of the bipartisan agreement or not.

"And if not what does he propose to do to try and get peace in Northern Ireland."

The Northern Ireland secretary's ceasefire decision has infuriated Unionists. They say that a recent murder, the discovery of an alleged gun-running plot and a string of death threats to people suspected of "anti-social behaviour" are all proof that IRA violence has not stopped.

Hague 'entitled to criticise'

But Mr Hague was defended by former Tory defence minister Michael Mates.

He said that it had been "a very serious error of judgement" for the government to say the IRA ceasefire was still intact and that the Conservative leader had been "entitled" to point that out.

Michael Mates: Ceasefire decision was 'very serious error of judgement'

Mr Mates said that when Dr Mowlam was in opposition she had been equally vocal in her criticism when she perceived any flaws in the then Tory government's Northern Ireland policy.

He insisted that the Tories remained committed to supporting the government in its efforts to secure a lasting peace.

Mr Hague's attack on government policy also coincided with a fresh appeal by Dr Mowlam to the province's political parties to participate in the review of the Good Friday Agreement.

The review is intended to end the peace process stalemate over paramilitary arms decommissioning.

BBC News' Carole Walker: Tories accused of breaking bipartisan arrangement

It is due to begin on Monday and will be chaired by former US senator George Mitchell.

Neither Sinn Fein nor the Ulster Unionists have decided yet whether they will take part.