RATS FED on a diet rich in GM maize have developed abnormalities to internal organs and changes to their blood, according to the Independent on Sunday.

The newspaper revealed details this Sunday (22 May) of a secret study carried out by Monsanto indicating that rats fed the GM maize had small kidneys and variations in the composition of their blood.

These health problems were absent from another batch of rodents fed non-GM food as part of the research project, the newspaper said.

Monsanto dismissed the abnormalities in the rats as “meaningless and due to chance, reflecting normal variations between rats”, according to the Independent on Sunday.

Doctors, however, told the paper that the changes in the blood of the rodents could indicate that the rats’ immune system had been damaged or that a disorder such as a tumour had grown and the system was mobilising to fight it.

A government source said ministers were worried by the findings, and that they had called for more information.

Dr Vyvyan Howard, senior lecturer on human anatomy and cell biology at Liverpool University, called for the publication of the full study by Monsanto.

Only last week European countries failed to reach agreement over whether the GM maize – called MON 863 – should be sold in the EU.

Britian and nine other countries voted in favour.