Nick Clegg has said he does not "knowingly" give his children GM food and said the government should take a "cautious" approach towards the adoption of the crops, stressing it was important not to take risks.
His warning came as environment secretary Owen Paterson is pressing for a relaxation of strict EU rules on the cultivation of GM crops.
Paterson has said GM crops are probably safer than conventional food and offer "wonderful opportunities to improve human health".
However, last week Downing Street repeatedly refused to say whether David Cameron would eat GM food himself or feed it to his family.
Asked on his weekly radio phone-in on LBC 97.3 whether he would give his children GM food, Clegg said: "I don't knowingly feed my children GM food.
"I think what you have got to do on this very vexed issue is just always be led by the science, be cautious, take cautious steps, don't obviously take risks, particularly where people have concerns about contamination between GM crops and non-GM crops. It is like a lot of these dilemmas, it is about getting the right balance.
"I take science-based precautionary approach. I would never say 'no' for ever to new technologies - I don't think we should do that in life generally - but you have got to approach it cautiously.
"That is what the European Union has been doing for some years now."
Clegg said that in practice the issue of whether to eat GM foods did not generally arise as they were not generally available in the UK.
"To be honest I can't ever knowlingly remember picking up anything in the supermarket, does this say whether it is GM or not. It is not the basis on which we feed our children," he said.
"You have got to remember that there is no commercial growing of GM crops in this country at all and the European Union laws are incredibly, incredibly strict.
"If you don't grow the stuff in the first place you can hardly feed it to your children."
Downing Street said that Cameron believed it was important that the scientific evidence relating to GM crops was properly examined.
"The most imprtant thing is that all the food on all the shelves in British shops is safe," a No 10 spokesman said.Suggest a correction