BBC Political Editor Robin Oakley: "The Tories are pressing for tougher labelling"

He said he was sure the prime minister eats foods containing GM ingredients and has no worries about health effects.

The prime minister would not follow the example of former Conservative minister John Gummer who fed his children beef burgers to dispel worries over BSE, he said.

But Mr Blair has "a sense of frustration that the debate is not being conducted in as fully informed manner as it could be", the spokesman said.

Tony Blair: "Strongly believes GM foods are safe"

"The prime minister is very strongly of the view that this product is safe. He has no hesitation at all about saying that."

But Dr Doug Carr, Director of Greenpeace, said Mr Blair's actions would not reassure the public.

He said: "Blair's frustration is nothing compared to the 81% of the population that are saying they want organic rather than genetically engineered food."

The Food and Drink Federation, which represents the food manufacturing industry, welcomed Mr Blair's statement.

A spokeswoman said: "It is time that the voice of reason had its say in this debate."

The renewed backing for GM food from the top of the UK Government comes as the opposition call again for a moratorium on the commercial planting of GM crops.

The Conservatives have stepped up the pressure on the government in what they say is a bid to clear up the confusion.

The BBC's John Sergeant: The same sort of dilemma as the Tories were in over BSE

Shadow Trade Secretary John Redwood has published a draft bill calling for clearer labelling of GM foods.

At the same time, he repeated calls for the resignation of Cabinet Office Minister Jack Cunningham and Science Minister Lord Sainsbury.

Mr Redwood said the government had been "very arrogant" over the issue.

John Redwood: Government had been arrogant

Dr Cunningham has repeatedly dismissed such demands for a temporary ban.

He has said GM foods on sale in Britain are safe and that there is no medical evidence to suggest they should not be allowed into the food chain.

However, the Conservative bill calls for clearer labelling for all GM ingredients contained in food.

Cross party consensus on the issue of GM foods should be harnessed to cleared up the growing public concern, Mr Redwood said.

The government had created the crisis in confidence but by supporting the bill they could help clear up current confusion.

Throwing the down the gauntlet to the government, he said: "I hope the government will respond quickly and positively, as they have now said that they agreed with the Conservative Party's position that customers should have the right to choose.

Jack Cunningham: Tories have demanded his resignation

"I would be happy to amend the draft bill if the government's lawyers had a better way of achieving the same ends."

The government had to speed up its response to the growing crisis in confidence in GM foods, Mr Redwood said.

Ministers were damaging that consumer confidence by their dithering and attempts to introduce such foods by stealth.

The government had become too close to the biotech companies behind GM foods, he went on.

Mr Redwood said: "We are calling for independent ministers to be in charge of this issue.

"We don't believe Lord Sainsbury is properly independent. He made his mind up about GM foods years ago as a businessman.

"Mr Cunningham has shown he isn't independent. He has lost the confidence of the public."