Ministers are threatening to take unprecedented steps under the devolution agreements with Scotland and Wales to ensure that they accept GM crops, The Independent on Sunday can reveal.
Margaret Beckett, Secretary of State for the Environment, made it clear last week that the devolved administrations - which are much more sceptical about the technology than the Westminster government - could not have a veto on planting GM maize across Britain.
Her move, immediately described by environmentalists as "bullying", is bound to lead to a storm of protests in both devolved assemblies, where GM crops have become an explosive political issue, and could cause a constitutional crisis.
Last week, as originally predicted in The Independent on Sunday last October, Mrs Beckett announced that Britain would ban GM oilseed rape and beet but gave a tentative go-ahead in principle to cultivating GM maize.
But her announcement was much more provisional than Mr Blair and his ministers had wanted, largely because of resistance from the Scottish and Welsh administrations, which delayed it for weeks. In the end it stopped short of giving specific permission to grow the maize while tough conditions for cultivating it were worked out and the public is consulted about how to minimise the spread of genes from the GM maize to neighbouring conventional and organic crops, and how to compensate farmers whose produce is contaminated.
The Welsh and Scottish administrations have to be brought on board because by law no GM crop can be grown anywhere in the UK unless there is a joint agreement by all the governments of the United Kingdom.
Last week the Scottish First Minister, Jack McConnell, said that "almost all members of the Parliament are sceptical about GM crops", and included himself. And Carwyn Jones, the Welsh Minister for Environment, Planning and the Countryside, stressed that his administration would take the "most restrictive approach possible" within the law.
Against this background the Department for Environment, Food and Rural Affairs made it clear last week that the devolved governments could not be allowed to have a veto on growing the maize. While stressing that Westminster was "working with all the devolved administrations to see if we can develop ... measures acceptable to us all", the department insisted: "If we do not reach joint agreement ... under the appropriate legislation, there are more general mechanisms to reach mutual agreement."
Senior officials made it clear that that would involve invoking, for the first time, a provision under the devolution agreement for the Government to convene a joint ministerial committee to resolve the issue. Normally this would be chaired by Tony Blair and consist of Mr Prescott, Mr McConnell, Rhodri Morgan, the Welsh First Minister, and two other ministers from Wales and Scotland.
If even this failed to reach agreement, sources said, Mr Blair, whose commitment to technology remains undiminished, could impose the GM maize by legislation at Westminster.
Even the threat of this is likely to cause a great storm of protest in both the Welsh and Scottish assemblies, and any attempt to impose the crop would be bound to lead to a full-blown constitutional crisis. The Government can avoid this by using another back-door route, using general permission to grow the crop in the European Union to bypass the need to reach agreement with Wales and Scotland, but this would be likely to cause even more controversy.
Pete Riley of Friends of the Earth said that invoking the devolution settlement would be "an extraordinary act by Mr Blair, putting the financial interest of the biotech companies ahead of democracy in Wales and Scotland". He called the threat to use the measure "bullying" and said that any attempt to force through GM crops would lead to a "huge and angry reaction" in both countries.