Tony Blair has been plunged deeper into the row over "Frankenstein foods" after refusing to sack science minister Lord Sainsbury over his links with the industry.

The BBC's John Sergeant: "The government are becoming increasingly impatient"

In a calculated attempt to turn the tide of public opinion, the prime minister insisted for the second day running that a ban on GM food would be "extremely foolish."

And he claimed calls for the minister and supermarket boss to be sacked were based on "hypocrisy and total opportunism" by the Tories.

The latest row erupted after it emerged Lord Sainsbury owned a company which developed genetically-modified foods.

Backed by Mr Blair, the minister has insisted there has been no conflict of interest between his business links and government policy.

He also confirmed that he had left the room during ministerial debates when the issue of GM foods was raised.

Conflict of interest

But that left Tories claiming that the very admission that he had felt it necessary to leave the room meant he knew there was a conflict of interest.

William Hague fears a conflict of interest

William Hague declared: "The basic truth of the matter is that he is too close to that industry to be objective about these matters and we need ministers who are objective."

And there remains confusion over exactly how effectively Lord Sainsbury insulated himself against government discussions and decisions on GM foods.

The Tories managed to win an emergency Commons statement from the government over the issue - but it failed to answer many of the key questions.

Combative agriculture minister Jeff Rooker was put in to bat for the government in the clear hope he would finally get some science into the argument.

This was clearly meant to be the latest assault in the government's counter attack against what ministers believe is an ill-informed debate over GM food.

But, like so many Commons debates on issues that have gripped the public, there was far more heat than light.

The Tories are frustrated by the fact that, while they should be on to a winner with this one, they are hampered by their own record.

Personal credibility

The scares over salmonella in eggs and, more importantly, mad cow disease have left consumers anxious and distrustful of both scientists and politicians.

By even raising the subject, they remind consumers of the food scares and inept handling of them, that erupted under their administrations.

Tony Blair, meanwhile, has also pegged his personal credibility to the issue with his recent statements declaring total support for GM food.

He even came close to repeating the mistake of former Tory Minister John Gummer by feeding his children burgers to prove beef was safe.

And, for the time being at least, he is fighting an uphill battle in his attempt to bring some clarity to the debate.

Revelations about ministers' involvement in GM foods will only fuel public anxiety.

Lord Sainsbury denies conflict of interest

Lord Sainsbury has issued a strong denial of any conflict insisting that, while he owned a patent on a biotechnology product called a "translator enhancer" it was transferred to a blind trust along with his shares in Sainsbury when he joined the government.

The patent was declared in the register of interests at the House of Lords before becoming a minister, he said.

Unpleasant and wrong

The prime minister lost no time in riding to his minister's defence, declaring: "Let me say two things. First of all with David Sainsbury, the hounding of him is unpleasant and wrong.

"There is no conflict of interest whatsoever, and he has followed the rules to the letter, as indeed he should do.

"Secondly, with GM food, this is a new science and a new technology so we should proceed with very great care and very great caution, and with a strongly regulatory process. That is precisely what we are doing."

But for once Mr Blair's skill at capturing the public mood appears to have to let him down badly and he needs to do much more to reassure consumers that their health is safe in the government's hands.