Conservative ministers have been accused of risking the future of the United Kingdom after they pushed through plans to restrict the voting rights of Scottish MPs.

SNP MPs claimed the move would enhance the case for independence by driving a wedge between England and Scotland that their party would balk at.

One SNP MP also claimed ministers were exacting "payback" for Scots support for the SNP during the General Election, an accusation furiously denied by the Conservatives.

Controversial proposals for ‘English votes for English laws’ (Evel) were passed by a majority of just 42 MPs.

Tory ministers said that the move was needed to restore “fairness” to the devolution settlement – and predicted that it would safeguard the Union.

But opponents accused ministers of gerrymandering and creating a tier of “second class" MPs.

There was also an outcry after ministers indicated that the proposals might be much farther reaching than initially thought.

Chris Grayling, the Leader of the House, suggested that Scottish, Welsh and Northern Irish MPs could be barred from a vote on the expansion of Heathrow Airport.

Mr Grayling said that the issue could be branded 'England-only', despite the significant impact on the rest of the UK.

Under Evel, the Speaker will be required to judge if a Bill is ‘England only’ or ‘England and Wales only’.

This certification will trigger a new stage in the Bill in which only English MPs will be allowed to vote.

Mr Grayling said that it was right that laws could not be imposed on England without the consent of English MPs.

The UK Government previously pulled a planned vote on Evel in the face of potential parliamentary defeat.

Sine then it has accepted a number of changes at the suggestion of a powerful Commons committee, including to allow the Speaker to set out why he judges a Bill English only.

Estimates resolutions, which decide public spending, will also be outside of the new rules, which Mr Grayling said should avoid problems with so-called Barnett consequentials.

These govern the amount of money transferred to the Scottish Parliament as a result of decisions in England.

Mr Grayling said that the proposals would “bring fairness to our devolution settlement and it is fairness that will secure the future of our Union".

He rejected accusations that Scottish, Welsh or Northern Irish MPs would be excluded as “nonsense”.

But the SNP’s Pete Wishart described it as a “dark, dark day for Scottish members of parliament”.

"The Tory government claims this is about saving the union," he said.

"The truth is all Evel does is enhance the case for independence.’’

He also warned that the move would set Scottish MPs against the Speaker and could lead "all the way to the Supreme Court".

Fellow SNP MP Tommy Sheppard accused Tory ministers of "pandering" to the English nationalism of Ukip.

He also claimed that Evel was “payback” for the SNP’s success north of the border in this year’s General Election.

“Just because it is in your manifesto it does not make it right,” he urged Tory MPs as he warned the reforms would “will drive a wedge between our two countries greater than any that I would drive between them”.

Labour’s shadow Scottish Secretary Ian Murray denounced the changes as "an incomprehensible mess".

He accused the Tories of taking "a wrecking ball to parliament".

"David Cameron always puts his party before the country and, today, he's put his party before parliament," he said.

Chris Bryant, the shadow leader of the House, warned the move was a "charter for breaking up the Union".

Labour’s Gerald Kaufman, the Father of the House, declared it “a day of shame for the House of Commons”.

He attacked the debate as “one of the nastiest, most unpleasant I have attended in 45 years”, by “a government with no respect for the House of Commons”.

But Tory backbencher John Redwood said that the plans delivered “justice” for England.

English MPs must give their 'consent' to any Bill deemed England-only, but Scottish MPs could still have the power to veto Bills as all MPs will get a final vote on legislation.

In the past couple of months Conservative ministers have pulled a number of votes, including on fox hunting, for fear they would lose because of the votes of Scottish MPs.

On Heathrow, Mr Grayling said that votes on flight slots or airspace capacity would be done "on a UK-wide basis".

If, however, the vote on a third runway was presented in parliament as an issue about a planning application "it might be very different", he warned.

MPs voted for Evel by 312 votes to 270, a majority of 42.

David Cameron has been criticised for announcing his plans to restrict the voting rights of Scottish MPs just hours after the independence referendum result was announced last September.