NO one will believe David Cameron ever again if he fails to honour the three-party pledge on granting more powers to Scotland, Labour has insisted.

Senior sources close to Ed Miliband, speaking at Labour's annual conference, expressed anger and dismay at the Prime Minister's statement, given within an hour of Friday morning's No vote, in which he linked progress on giving more powers to Scotland with meeting demands from Tory backbenchers on so-called English votes for English laws.

After Alex Salmond denounced Mr Cameron for shamelessly reneging on the deal, one senior Labour source insisted Mr Miliband's position had not changed one jot and he would do everything in his power not to allow the Tory leader to "f*** this up".

But he stressed: "If Cameron reneges on this, everyone in the UK will say this man can never again be trusted by anyone."

Calling for clarification from Downing Street, the source pointed out either the PM had introduced a new condition, in which case he ran the risk of incurring the wrath of not only the voters of Scotland but also people right across the UK, or he had not, in which case he would face the anger of Tory rightwingers.

"We're not going to be political cover for Cameron with his backbenchers," insisted the source.

This morning, Mr Miliband made clear he had not been told by Mr Cameron of his linking devo-extra for Scotland with devo-extra for England. An aide made clear that if it had been made clear to Scottish voters ahead of last Thursday's referendum, then "there would have been a Yes vote".

One party source said: "Cameron now has to do the right thing and get this sorted out. He cannot start playing political tricks with the British people."

Earlier, the Labour leader was adamant about his own position on the "vow" to Scotland, saying: "We are going to deliver on that promise; no ifs, no buts."

He stressed how there was not a simple solution to the English Question but made clear he was open to English MPs having "greater scrutiny" of English laws. His proposal is to have a public consultation on devolving more power to England with a constitutional convention to pore over the details - but after the May 2015 General Election.

Alistair Darling, who led the Better Together campaign, described the tripartite promise as "non-negotiable" and warned if the agreed timetable was not met, then those who had blocked it would "pay a very heavy price for years to come".

But Mr Cameron wants to use the same timetable for giving extra powers to Holyrood - a White Paper by November, draft legislation by January with implementation next year - for granting more devolution to England.

Tomorrow at Chequers, he will meet Tory backbenchers to flesh out his plans for decentralising power from Whitehall to the English regions and cities.

But it appears the PM's proposed offer to England is causing a rift within the Lib-Con Coalition with Nick Clegg insisting the extra powers for Scotland ''cannot be made contingent on other constitutional reforms''.

A Downing Street spokesman said a timetable for more powers had been set out, adding: "This Government has delivered on devolution and we will do so again in the next Parliament."

Yet Mr Salmond claimed the Labour and Conservative positions were now "irreconcilable".

He explained: "David Cameron doesn't think he can carry his own backbenchers, never mind the threat from Ukip, unless he links Scottish progress to changes in England.

"Ed Miliband doesn't want to do that because Labour would lose their majority over English business in the House of Commons. That is the log-jam the Westminster leaders got themselves into...Shouldn't they have thought of that before they made a solemn vow and pledge to the Scottish people?"

The First Minister added: "It's the people who voted No - because they believed these commitments from the Westminster leadership - who are feeling most angry, most hurt, most disappointed in Scotland today. The wrath of Khan will be as of nothing to the wrath of a No voter who has been gulled by the Westminster leadership."