David Cameron is facing a ­backlash from Tory MPs after throwing his weight behind a last-minute pledge to guarantee more powers for the Scottish Parliament.

A number of senior ­Conservative backbenchers demanded curbs on the rights of Scots MPs if, as promised, plans to give Holyrood greater control over income tax are fast-tracked through Westminster next year.

Christopher Chope, the MP for the Hampshire seat of Christchurch, said he would attempt to block the transfer of more powers unless wider constitutional changes were agreed.

Another Tory, Bernard Jenkin, chairman of the Public Administration Select Committee and a frequent critic of the PM, said Scots should be barred from becoming Chancellor.

They spoke out after Mr Cameron, Ed Miliband and Nick Clegg promised "extensive" further devolution if Scots vote No tomorrow.

They said the UK "exists to ensure opportunity and security for all by sharing our resources equitably across all four nations".

They also suggested that the Barnett formula for allocating government funding - which has been criticised by some English MPs as unfairly generous to Scotland - would continue unchanged.

Though the three main UK parties have tabled different proposals for further devolution they have agreed to iron out their differences and produce draft legislation by January under a timetable proposed by Gordon Brown.

Asked on Monday night about the possible consequences for England, Mr Cameron said he was not "remotely" near backing a devolved English parliament.

However, Mr Chope said he would vote against a more-powers package unless there was a wider examination of the balance of powers within the UK as a whole. He told BBC Radio 4's World at One: "I certainly think that people in Scotland should recognise that this is a 'pledge' by party leaders, but that is not a guarantee that that would be implemented in the United Kingdom Parliament."

Fellow Tory John Redwood demanded an "honest" and "more grown-up" constitutional settlement if Scotland stays.

"If Scotland is going to decide some tax rates as well as spending for itself, so should England. What is good enough for Scotland is good enough for England," he said. "It must mean the end of Scottish MPs voting on English schools or English hospitals whilst being unable to do the same for their own.

"There must be no question of Scotland setting her own income rate and then sending MPs to Westminster to help set ours."

Another Conservative MP Rob Wilson said England would not tolerate "another downgrading" if Scotland gained more powers.

Calling for an English executive with its own first minister and finance minister, Mr Jenkin, said: "We could never have a ­Scottish UK Chancellor setting English taxes in England at the annual budget but not in his or her own constituency.

Danny Alexander, the LibDem Chief Secretary to the Treasury, today seeks to reassure voters that powers over income tax and welfare will be delivered swiftly.

Writing in today's Herald, he says: "If Scotland votes 'no thanks', as I fervently hope will be the case, then Home Rule will swiftly follow."

But a spokesman for Yes ­Scotland said: "The reality is that the only way to guarantee Scotland gets all the powers we need to create jobs and protect our NHS is with a Yes vote on Thursday - so that we can use our enormous wealth to create a better and fairer country."