Ministers must not approve commercial planting of GM crops in England, until it is proved safe, say the Lib Dems.
Chris Huhne said responses to a Defra survey show planting should not be allowed until ministers can prove non-GM crops will not be contaminated.
Most respondents opposed Defra's plan to allow GM crops to be grown in fields at least 35m (114ft) from non-GM crops.
A Defra spokesman said they would await the results of three reports, due next spring, before plans are taken further.
No commercial GM crops are yet grown in the UK and are not expected for several years, but the government wants to have measures in place in England for the "coexistence" of GM, conventional and organic crops.
EU regulations state that food containing more than 0.9% of genetically modified ingredients have to be labelled as GM produce - even if they were grown as a conventional crop.
The government is proposing having compulsory separation distances between crops to minimise cross pollination of non-GM varieties.
And farmers intending to sow GM crops would be required to notify neighbouring farmers.
The three-month consultation attracted 11, 676 responses - 11,442 from "members of the public".
Defra said about 80% were in the form of stock letters or petitions, which conveyed a "basic disagreement" with Defra's proposals and said 0.9% was too high and in organic produce, it should be less than 0.1%.
Of the remaining 20% about 1,370 people registered a "general opposition to GM crops" while about 390 people were mainly concerned about "a perceived threat to organic farming".
Other responses included those from farming organisations, councils, organic farmers, biotechnology companies, scientific bodies and other organisations.
Defra said responses were "polarised" between pro and anti-GM views - with some favouring the government's proposals as "pragmatic and proportionate".
Mr Huhne, environment spokesman for the Liberal Democrats, said: "People want to be safe and not sorry on GM foods, as the overwhelming bulk of responses to the government's consultation show.
"Ministers should not give any go-ahead for commercial planting until they can state confidently that GM varieties would not contaminate non-GM foods and that they are safe.
"This is essential for consumers who prefer non-GM foods, but also for organic farming which is the fastest growing part of British agriculture."
Environment Minister Phil Woolas said the government was still awaiting three important research projects on co-existence, due to be published next spring - and EU guidance on labelling GM presence in seeds. But the intention was to have "pragmatic measures in place".
He said: "GM crops may be approved for cultivation here in the future, if they pass the rigorous safety assessment procedure that is in place.
"We need to be ready for that possibility and the consultation on coexistence measures has been an important step forward in that process." ( BBC )