Tory leader William Hague said the bill, which will be set before Parliament later this week, will follow the advice of the government's advisory body English Nature.

"Since the government have refused to act, we will initiate legislation in the Lords this week," he said at a Westminster news conference.

"It is easier for bills to be introduced by private members to proceed in the Lords but of course its eventual fate will be determined by the government majority in the Commons."

The Tories say they have learned from BSE

Mr Hague said he would have again raised the issue at Prime Minister's Question, if the House of Commons had been sitting this week.

"If there had been question time today, I would have asked the prime minister if he would support this bill.

"I would also asked him if he would instruct all ministers to publish all the advice given to them by scientific advisers. And if they haven't been given any advice, why not and why haven't they asked for it."

Mr Hague said he still believed the GM foods on sale in the UK, which were approved by the previous Conservative government, remained safe.

"I don't think scientists can fully be able yet to assess what the ultimate consequences will be but there is no evidence they are unsafe."

The party's concern now was the effect on the environment if GM crops started to be planted without rigorous scientific tests.

He said he was not scaremongering but reflecting widespread public concern about the possible risks of GM food.

"I wouldn't call them 'Frankenstein foods'. It is too serious an issue to use terms like that. But people who are not interested in politics feel very strongly about this issue.

"The Conservative Party is learning and listening and changing and we have learned public confidence in food safety is very important and we remember BSE."

He added that he would rather not eat GM food, although he was sure he did as it is hard to avoid.

Lord Sainsbuy should be moved not removed, Hague says

"If I had to choose, if I saw on a shelf - these are GM foods and these are organically-grown foods, I would choose the organically-grown foods."

But the Tory leader repeated his attack on the government's handling of the issue.

He said: "They have sat on the evidence, they have ignored scientific advice, they are contradicting themselves hourly, they have a science minister who has to leave the room every time someone says the word 'tomato' - it's a ludicrous state of affairs."

Asked if he was calling for Science Minister Lord Sainsbury, who has shares in a GM company held in a blind trust, to resign, Mr Hague said he was not.

"I am calling for him to be moved to another job. I've nothing against Lord Sainsbury, I'm sure he can bring a lot to the government, but he's obviously too close to this matter to take an objective view on it."

He added that the government had been slow to recognise the true depth of public feeling on the issue of GM food.

"Two weeks ago I asked about this matter at Prime Minister's Questions. Tony Blair looked at me in amazement as if this subject was not worthy of a response at question time."