"This is a worldwide victory for consumers and farmers," said Friends of the Earth International in a press release.

"Virtually every major wheat-user in the world had already rejected this product before it even was allowed on the market. This must be one of the most rejected products ever developed."

Greenpeace International claimed credit for "years of pressure from environmental groups, the consumers [and] our cyberactivists."

"Strong rejection of GE [genetically-engineered] wheat from virtually every corner of the globe once again showed the resistance to GE foods," said Greenpeace activist Pat Venditti.

Sue Mayer, a campaigner with British group Genewatch UK, said Monsanto's announcement had come as a surprise.

The pullback was "hugely significant", she told AFP.

"Wheat is a very, very important market for them, offering vast potential for profits, so it can't have been an easy decision for them."

Monsanto discreetly announced on Monday it was "realigning research and development investments" and would defer all further efforts to introduce its Roundup Ready wheat.

This strain has a gene added to it that makes the plant resistant to its herbicide Roundup Ready. That means a farmer only has to spray his fields once, killing the weeds but not the crop.

Monsanto had spent six years on the product and lavished a sum reported to be in the hundreds of millions of dollars.

But it met with resistance from buyers in Europe and Japan and from North America's wheat belt.

"Farmers overwhelmingly opposed the introduction of Roundup Ready wheat, which offered few agronomic benefits and threatened to destroy premium markets for their crop," Ken Ritter, chairman of the Canadian Wheat Board (CWB), said.

Monsanto did not say that the pullout was definitive.

"We will continue to monitor the wheat industry's desire for crop improvements, via breeding and biotechnology, to determine if and when it might be practical to move forward with a biotech wheat product," Carl Casale, the corporation's executive vice president, said.

Although environmental groups claimed credit for torpedoing Roundup Ready wheat, Mayer said the biggest factor was probably the farmers.

"They have been worried for years, seeing the response from [North American] bakers and from buyers in Europe," she said. US exports of soybean and corn have been badly hit by the GM controversy and this would also figure in their thinking.

Monsanto has already backed away from marketing GM potatoes after running into flak from fast-food companies.

Its German rival, Bayer CropScience, the agrochemicals arm of German giant Bayer, announced in March that it would scrap plans to market herbicide-resistant corn in Britain.

The latest move comes as the European Commission reflects on whether to give the green light to growing a strain of GM corn called Bt-11, which exudes a toxin that kills an insect pest.

The Commission was handed the job last month after European Unionministers failed to reach a majority decision, thus keeping in place a de-facto moratorium on this crop across the world's biggest trade bloc.

Defenders of GM crops say they offer financial benefits and enhanced yields to farmers and are no danger to health or the environment.

Opponents say too little time has elapsed to draw this conclusion, and point to sketchy evidence that these plants can affect biodiversity and encourage the emergence of herbicide-resistant weeds.

TERRA.WIRE