Alex Salmond has hinted at another referendum on Scottish independence taking place as he threatened to exact "revenge" if pledges promised by the government are not fulfilled.
As MPs in the House of Commons debated the promise of more powers for Scotland, the SNP leader accused David Cameron of "reneging" on pledges promised in the run up to the historic vote and warned there would be consequences if the No parties fail to deliver more powers for Scotland.
The debate erupted into a heated clash between William Hague and Former Prime Minister Gordon Brown, the latter of whom argued that "crude" Tory plans risked undermining the UK in the wake of the referendum.
Salmond's comments also came as a senior Labour MP warned that the refusal of some supporters of independence to accept the result of the 55% to 45% 'No' vote will "poison" politics in Scotland.
Glasgow South West MP Iain Davidson, the chairman of the Commons Scotland committee, told MPs today that politicians and voters should "accept that there was a clear and decisive result".
"It appears that no form of devolution will satisfy those who are in favour of separation," he said. "We ares starting to see not just an unhappiness about the result but an actual rejection of the result. A myth of betrayal is being put forward."
Davidson said there was now a "grievance a day mentality" on the part of the SNP and supporters of the unsuccessful 'Yes' campaign. "That is going to poison, potentially, Scottish politics," he said.
But Salmond has insisted that Cameron is set on letting down Scottish nationalists.
"The Prime Minister started the process of reneging on the commitment when he came out of Downing Street hours after the referendum and said that progress in Scotland should be in tandem with ... constitutional change in England. Even Gordon Brown is finding it difficult to stomach," he told BBC Radio 4's Today programme.
Indicating that he did not view another referendum as completely off the agenda, he added: "What I said was that the referendum was a once-in-a-lifetime opportunity," he said.
"My view is that constitutional referendums came along once every political generation - about every 20 years or so.
"Circumstances obviously can change. Clearly, if you had a situation where three leaders made such a public vow - not even a political promise but a vow - in the last few desperate hours when they thought they were losing the referendum campaign and then reneged upon it, then that would obviously be a very, very substantial change of circumstances.
"These matters ultimately are for the people of Scotland to decide. It is for the people of Scotland to decide whether it is satisfactory to be conned and tricked by Westminster leaders, or they will exact a revenge at the ballot box."
But Leader of the House of Commons William Hague said Salmond was "almost looking for and hoping for some sense of betrayal".
The Tory minister told Today: "Let it be very clear that every commitment made by not only the Conservative but Labour and Liberal Democrat parties about what would happen if the result of the Scottish referendum was No, every commitment has so far been kept and will be.
"We have said, the Prime Minister and I have said, that those things should go in tandem. But they are not tied in the sense that one is dependent on the other.
"The commitments to Scotland are unconditional and will go ahead - this is an absolute 100% clear commitment that will go ahead whatever we decide or don't decide about England.
"But it is our view that fairness to the whole of the UK means the party should also agree on the same timetable the consequences for Scottish MPs voting on English matters.
"If they can't, then of course it will be a matter we all debate in the general election campaign. This is a democratic country. The people will decide."
Earlier, Hague clashed with Brown, who warned "nations can collapse by accident".
Brown said excluding MPs from non-English constituencies from some votes would erode the "stability and harmony of the British constitution".
"You cannot have one UK if you have two separate classes of MP," he said. "You cannot have representatives elected by the people who are half in and half out of the law making process."
Brown has already warned that Cameron’s plans to ban Scottish MPs from voting on English laws risk breaking the “fragile” Union.
The former Labour leader said combined with plans to devolve total control over income tax to Holyrood, Cameron's proposals were a “lethal cocktail” that could end the United Kingdom.
Brown accused the PM of playing “fast and loose” with the constitution, prompting mockery from the SNP who said his input to the debate since the vote had become “increasingly surreal”.
Cameron today accused Labour of "not being interested in fairness" for the UK after it decided to boycott talks on English votes for English laws.
Ed Miliband's party denounced the talks being led by Hague as "a closed-shop stitch-up" when "proper reform" is needed.
But the Prime Minister rejected the suggestion that he was playing politics with the Union following the vow made to the people of Scotland during the referendum campaign.
He said: "What we need is obviously more devolution for Scotland but a settlement that's fair for the whole of the United Kingdom.
"I think it's a matter of great regret if Labour are going to walk out of this Cabinet committee which they could join in and make their suggestions.
"But obviously they are not interested in fairness across the United Kingdom so we will have to work hard with other partners to make sure we deliver."Suggest a correction