French Prime Minister Jean-Marc Ayrault says he is prepared to call for a wider European ban on genetically modified produce following an alarming new study that throws the safety of the food into doubt.

The report claimed that 200 rats fed GM corn produced by US firm Monsanto had suffered tumours as big as ping-pong balls.

Ayrault has ordered that the scientific validity of the study be checked by the country’s health watchdog.

So far Monsanto has not responded to the findings.

But scientist Joel Spiroux has called for new rules on GM foods:

“Current regulation tests are conducted over three months, but the really serious diseases, such as the death of rats due to tumors, occur only in the fourth month,” said Spiroux.

“Therefore these tests give no real information about the effects of genetically modified food on health over a lifetime.”

The study has also been forwarded to the European Food Safety Authority.

Currently, 46 varieties of GM products are allowed in the EU. They include corn, cotton and canola oil varieties and one type of potato and beetroot.