THE growing row over 'English votes for English laws' intensified last night, as the SNP and Tories accused each other of "disrespecting" the people of Scotland.

In an angry exchange of letters between Edinburgh and London, SNP MP Pete Wishart told David Cameron his "disrespectful proposals" could hasten Scottish independence, while Scottish Secretary David Mundell wrote to the First Minister accusing the SNP of disrespect by talking up a second referendum after promising to accept the outcome of the first one.

Wishart, the SNP Shadow leader of the House, said it was "difficult to think of any measure more likely to undermine the constitutional integrity and future of the Union" than Evel.

Mundell defended the plan as "sensible and pragmatic" and supported by Scotland.

Under Evel, Scottish, Welsh and Northern Irish MPs would be banned from voting on key stages of "English-only" issues, as defined by the Commons Speaker.

A "double majority" of MPs would be required to enact English-only laws in future - a majority of those representing English seats, then a majority of the whole House.

However, the SNP argue many apparently English-only issues could have profound knock-on effects for Scotland, especially in terms of Holyrood's budget.

There is also cross-party condemnation of the Tory plan to introduce Evel by amending Commons standing orders, rather than through primary legislation.

Not only does this limit debate and scrutiny, it also prevents any legal challenge to Evel.

The new arrangement is meant to answer the West Lothian Question - the famous side-effect of devolution which means Scots MPs can vote on some English issues but English MPs cannot vote on the equivalent Scottish ones.

Commons Leader Chris Grayling told MPs on Thursday that Evel would bring "real fairness to our constitutional arrangements".

However Nicola Sturgeon called the plan "staggering in the extent... of its hypocrisy and incoherence", and Labour said it was "reckless and an outrage".

A close vote on the issue is expected on July 15.

In his letter to Cameron, Wishart accused the Tories of making a mockery of their claims in the referendum campaign that the UK was a family of equal nations.

He wrote: "The proposals are nothing less than a constitutional outrage that will see Scottish MPs cut out of voting on matters which impact Scotland and our budget. Quite simply, they will reduce the rights of Scottish MPs to protect the interests of their constituents.

"It is difficult to think of any measure more likely to undermine the constitutional integrity and the future of the Union which you claim to support.

"We will not stand for your party's attempts to see Scotland's voice stifled and our influence reduced. The SNP will oppose these plans at Westminster - and we ask you to think again on these disrespectful proposals which are damaging to Scotland."

In his letter to Sturgeon, Mundell said the plan contained "sensible and pragmatic steps which do nothing to limit Scottish MPs' rights to represent their constituents, but which do give MPs from other parts of the UK the chance to veto proposals which only affect their constituents".

He told the First Minister: "I believe these proposals will command widespread sympathy and acceptance in Scotland.

"I was very sorry once again to hear threats of a second referendum... simply because you disagree with the UK Government implementing what is, after all, a clear manifesto commitment. We voted overwhelmingly to remain part of the UK in September. If there is any disrespect being shown to the people of Scotland, it stems from an inability to recognise and accept that decision."