Both the GM corn, which carries the name NK603, and Roundup are the creation of US biotech company Monsanto.
The decision by the Russians to suspend authorisation for the American GM corn threatens to trigger a transatlantic commercial and diplomatic row.
Russia's consumer rights watchdog, Rospotrebnadzor, said today that it has suspended the import and use of the Monsanto GM corn.
Rospotrebnadzor said the countryâs Institute of Nutrition has been asked to assess the validity of the study.
It has also contacted the European Commissionâs Directorate General for Health & Consumers to ask for the EUâs position on the cornâs safety.
Consumer scepticism in the UK and Europe means GM corn is not on supermarket shelves here, however it is fed to farm animals, including hens, pigs and dairy cows.
Last week Monsanto said it did not think the French study would affect its license to export the NK603 to Europe but would wait to hear from EFSA.
The company said: 'Based on our initial review, we do not believe the study presents information that would justify any change in EFSAâs views on the safety of genetically modified corn products or alter their approval status for genetically modified imports.'
The biotech industry and university researchers involved in GM research have mounted a major PR campaign over the last year to win over sceptical consumers.
In the past week, pro-GM scientists have been lining up to undermine the French experiments and criticise the way they were conducted.
However, a number of independent academics have praised the French teamâs work, describing it as the most thorough and extensive feeding trials involving GM to date.
Mustafa Djamgoz, the Professor of Cancer Biology, at Imperial College, London, said the findings relating to eating GM corn were a 'surprise'.
Prof Djamgoz, who describes himself as a neutral on GM, said: 'The results are significant. The experiments are, more or less, the best of their kind to date.'
However, he said that it is now important to ensure they are repeated with more animals by independent laboratories to confirm the outcome.
'We are not scaremongering here. More research, including a repetition of this particular study are warranted,' he said.
The professor said it will take two to three years to get a definitive answer.