Plans to grow GM maize in Britain are on a knife edge this weekend after a strong revolt in the Scottish Parliament and Welsh Assembly.

As revealed by The Independent on Sunday, ministers have threatened to quell the resistance to allowing genetically modified maize by an unprecedented use of powers in the devolution settlement.

Scotland's parliament has failed to reject the GM crop by just 60 votes to 59 after the Liberal Democrats supported it in defiance of their position in the rest of the UK.

The Scottish National Party's Roseanna Cunningham said that if just one Liberal Democrat had stood by their own policy "the executive would have been told Scotland must remain GM free".

On Wednesday this week the Welsh Assembly also faces the crunch, with the Lib Dems leading the opposition to the crop and set to prevail if they can get just one Labour member to rebel.

The Lib Dems' Mick Bates, who praised the IoS for exposing the devolution loophole, said that approving the crop would jeopardise work done to make Wales "a quality environment".

The votes are vital for Westminster, as all the UK administrations must agree before any approval for the crop's cultivation can be given.