Tony Blair warned against creating two classes of MP

He said voting in Westminster should involve MPs from all parts of the UK.

Conservative leader David Cameron recently backed calls for Scottish MPs to be prevented from voting on English matters.

But the prime minister said on Wednesday that it would be unwise to change the status quo.

The West Lothian question, first posed by Tam Dalyell in the 1970s, asked why Scottish post-devolution MPs should be allowed to vote on Westminster matters, but could not vote on devolved issues.

Devolution 'sensible'

Mr Blair told the Commons: "I think the important thing is to stress that England is of course the majority country within the United Kingdom and we actually vote through the money here in this House.

"In the constitutional settlement the vast majority of MPs who do that are English and I think devolution is a sensible way of keeping the United Kingdom together.

"I think it would be a very, very grave mistake indeed to end up with two classes of MP in this House."

Earlier this month more than 60 Labour MPs signed a motion warning that the Tory proposal to curb Scottish MPs' voting rights would trigger a constitutional crisis.