Fresh fears were raised over GM crops yesterday after a study showed they can cause liver and kidney damage.

According to the research, animals fed on three strains of genetically modified maize created by the U.S. biotech firm Monsanto suffered signs of organ damage after just three months.

The findings only came to light after Monsanto was forced to publish its raw data on safety tests by anti-GM campaigners.

They add to the evidence that GM crops may damage health as well as be harmful to the environment.

The figures released by Monsanto were examined by French researcher Dr Gilles-Eric Seralini, from the University of Caen.

Yesterday he called for more studies to check for long-term organ damage.

‘What we’ve shown is clearly not proof of toxicity, but signs of toxicity,’ he told New Scientist magazine. ‘I’m sure there’s no acute toxicity but who’s to say there are no chronic effects?’