A Brazilian regulator of genetically modified crops has warned the country's food safety advisory service that approval procedures used to assess GM crops skew science in favour of the biotech companies seeking licenses for their products.

Leonardo Melgarejo, a member of Brazil's GMO regulatory body CTNBio, representing the Ministry of Agrarian Development, sent the warning to health watchdog Consea. He said safety assessments are deeply flawed, riddled with data gaps and that differences observed in animals fed on GM feed have been dismissed as 'not biologically relevant' in the past, without scientific justification.

Sceptic organisation GM Watch EU welcomed the letter and claimed European food safety advisors at the European Food Safety Authority operate in a similar way.

Dr Melgarejo, who has previously been vocal in his opposition to GM crops, claimed approvals and releases of GMOs in Brazil thus far have been illegal because of negligence on the part of scientific regulators. His indictment of the use of GM in Brazilian agriculture also covered more familiar ground, such as issues of growing resistance in weeds and pests driving increases in pesticide use, and the return of older, more damaging chemicals.

These issues have been widely covered in the United States, where the controversial crops were first grown, but Dr Melgarejo said they pose just as grave a threat to Brazilian agriculture.  

In the letter, Malgarejo also questioned industry claims about the potential of the technology to achieve food security. He said, "The argument that world hunger will be overcome by productivity gains offered by genetic engineering remains an unfulfilled promise. In these 20 years of development of transgenics, almost all of GMOs involve Bt [those which exude a toxin to kill crop pests] and herbicide-tolerant technologies, which are not designed to achieve productivity gains."

The agrarian development official also warned that the approval of GM rice could become an issue once more. The rice has not yet been commercialised in Brazil; pressure from rice farmers who wanted to maintain trade links with Europe, where importers require GM-free rice, led to the withdrawal of an application bid in 2010.

However, Dr Malarejo said that, should a shortage of rice occur, EU regulators could cave in and agree to accept GM rice varieties, which would reopen the doors for its production in Brazil.

In Brazil, relations between farmers and biotech companies have been strained, due to a high-profile legal battle over royalties on seeds. Several major courts in Brazil have backed 5 million growers in their struggle to recover royalty payments made to seed giant Monsanto, though the company has challenged their rulings and approached farmers, offering discounts on royalties for its next generation herbicide-tolerant soybeans which features 'stacked' resistance.