A coalition of indigenous Mexican communities and environmentalists are demanding immediate action to stop what they are calling "genetic pollution" of traditional Mexican corn varieties.
At a conference to discuss the Cartagena Protocol on Biosafety in The Hague this week, the groups, including Greenpeace, called for a ban on the import of US corn into Mexico which they believe to be the source of rogue genes.
The calls follow ongoing controversial reports that transgenes from GM corn have been found in local varieties of corn in the Oaxaca region of Mexico. Last week in The Hague, scientists reported on two studies commissioned by the Mexican government's National Commission on Biodiversity (CONABIO) and the National Institute of Ecology (INE).
Jorge Soberon of CONABIO told ABC Science Online that an average of 10 per cent of corn in the areas studied had been found to contain transgenic DNA. This confirms one of the findings of a controversial report published last year in Nature but recently revoked by the journal in response to a deluge of criticism.
Soberon said the studies show evidence of two three telltale transgenic sequences: 35S, nos and B. thuringiensis (Bt).
"PCR searches for the 35S and nos sequences yielded positive results. ELISA tests for the expression of B. thuringiensis protein in leaves of corn yielded positive results. We are still waiting for the results of Southern blot tests," he told ABC Science Online.
He said the Mexican government has a policy against planting transgenic corn however food and feed seed is imported from the US where GM corn is grown.
The protest groups have also appealed to an environmental commission under the auspices of the North American Free Trade Agreement (NAFTA) to take action.
"This pollution not only affects Mexico but puts the world's food security at risk," said Miguel Ramírez Domínguez a community leader from Oaxaca. "Farmers around the world rely on these genetic resources to create new varieties," which adapt to changing environmental conditions."
Such findings are of huge interest to the Mexico-based International Maize and Wheat Improvement Centre (CIMMYT) whose job it is to act as a gene bank of plant varieties.
According to David Hoisington of CIMMYT, the institute itself is involved in researching transgenic maize and wheat but is very keen to keep each line separate and make sure it knows exactly what is in its germplasm.
However he is skeptical of the new reports from The Hague and about the concerns expressed by environmentalists.
He said CIMMYT's own tests have so far found no evidence of transgenes in their own genetic material, although they only looked for the 35S promoter sequence and herbicide resistance genes, and their sample size was limited by the number of seeds available in their gene bank.
While Hoisington admits that if precautions are not taken there is a "high probability" that transgenic corn genes will cross with local corn, he doesn't think the current transgenes are likely to be selected for.
However, like Soberon he agrees the research is yet to be done.
"It's one thing to prove there's transgenic sequences in the landraces of the people and another to find out what the effects are going to be - if any," said Soberon.
And while some are confident scientific research will keep ahead of the game, others are not and fear environmental damage from the spread of new transgenic varieties.
Should the Cartagena Protocol be implemented it would give countries the explicit right to refuse imports of transgenic material, on the basis of the "precautionary principle", as well as on socio-economic grounds
The protest groups at The Hague have called for immediate ratification of the Protocol and emphasise the cultural significance of corn to Mexico.
While the Protocol was adopted by more than 130 countries in January 2000, it has only been ratified by a few and will not come into force until it has been ratified by 50 countries.
Australia is yet to decide whether to become a member with critics such as the Australian Chamber of Commerce and Industry and the National Farmers Federation arguing the Protocol is a "de-facto trade agreement" which will jeopardise Australian farm exports.
They argue the precautionary approach will undermine "the more rigorous science based approach of the WTO".