Further devolution for Scotland will go ahead as promised regardless of the progress of controversial plans for English votes for English laws, David Cameron has insisted.

The Prime Minister told MPs that he is "very confident" that a pledge to hand over extra powers made by the three main Westminster leaders in the final days of the Sottish referendum campaign will be delivered as it was set out.

But he told the Commons Liaison committee voters will "get both" sets of constitutional reforms if he is returned to No 10 next year.

Asked if the pledge for additional powers to Scotland was free standing, he replied: "Effectively, yes. The pledge that was made by the party leaders I think is important and we'll meet the terms of that pledge in full, I'm very confident of that, which is that there should be further, particularly fiscal, devolution to Scotland, the power to raise taxes and spend money and there's a programme for delivering that."

In the course of the campaign, Mr Cameron, Deputy Prime Minister Nick Clegg and Labour leader Ed Miliband signed up to a commitment to hand extensive extra powers to Holyrood if Scotland voted to remain part of the Union.

But in the immediate aftermath of the vote rejecting independence, the Prime Minister said that there would have now to be a "new and fair" constitutional settlement for the entire United Kingdom.

In particular, he said there would have to be reform at Westminster to address the thorny issue of English votes for English laws, suggesting that Scottish MPs would no longer be able to vote on exclusively English issues.

His proposals drew a furious response from Labour - whose chances of forming a majority government at Westminster have traditionally depended upon winning a strong bloc of Scottish MPs.

Mr Cameron accused Labour and the Liberal Democrats of failing to set out clear plans for reform and insisted only the Conservatives would deliver extra powers for Scotland and English votes for English laws.

He added: "One is not dependent on the other. If I win the next election you get both. You get Scottish devolution and you get a proper answer to the English question.

"It's for the other parties to say what they will do and they ought to, in my view, make that clear.

"But I'm very clear, if you get me you get both."

The Smith Commission, which was set up by the UK Government to consider further devolution following the referendum, is due to report back next week and the recommendations will form the basis of legislation next year.

Mr Cameron said he was "very happy" with the way the commission was progressing but refused to rule out amending any of the clauses drawn up on the back of the Smith report at a later stage.

"I hope that isn't the case because what we are trying to do here is reach a consensus between the parties," he said.

"I'm confident that we will meet both the timetable and the substance."