The Science minister looked increasingly embattled last night after claiming earlier that he had stood aside from discussions on the issue.
Lord Sainsbury of Turville, whose supermarket shareholding is in a trust, has taken a leading role in a government consultation to which GM food and crops are central. The only food industry figure on an advisory committee for the exercise is from Sainsbury's.
The consultation will ask how the public views genetically modified crops, genetic testing and cloning. In December, Lord Sainsbury chaired a conference on it attended by groups including Greenpeace and Friends of the Earth. Earlier this month he took part in a debate on the exercise in a cabinet sub-committee on biotechnology.
John Redwood, the Conservative trade and industry spokesman, said Lord Sainsbury should resign. "He has a lot of explaining to do. A minister either has to sell all his shares or avoid contact with issues related to them. When is this minister going to obey the rules?" he said.
Yesterday, Lord Sainsbury said there was no conflict of interest. "I have not taken part in any government decisions or discussions relating to GM food policy," he said.
Later, his department issued a clarification, saying Lord Sainsbury took part in discussions that did not involve policy-making. The only recent policy-making discussion on GM food had taken place at the February cabinet committee meeting and the minister had left, a spokesman said.
"There is a very clear difference between actually making decisions and discussing policy matters, and having a general discussion," he said.
The Prime Minister, Tony Blair, attacked the Tories for "hypocrisy and opportunism". He added: "There is no conflict of interest whatsoever ... the hounding of Lord Sainsbury is unpleasant and wrong."
Norman Baker, the Liberal Democrat spokesman on GM foods, also attacked the Tories. "The real issues are the impact on the environment and the food chain. Until a few weeks ago the Tories thought GM stood for `General Motors'," he said.
Lord Sainsbury announced his public consultation on biosciences on 15 December, though a similar exercise had begun under his predecessor, John Battle. Its advisory committee included Alison Austin, from Sainsbury's, as well as scientists and a biotechnology company, though the DTI said she had been appointed by Mr Battle.
The exercise would explore the implications of progress in the biosciences, Lord Sainsbury's press release said. "Our long-term aim is to build public confidence in the Government's use of scientific information and know- how," he said.
In addition to his supermarket interests, Lord Sainsbury gave financial backing to two biotechnology companies, Diatech and Innotech Investments. Yesterday he denied a report that he owned the patent for the cauliflower mosaic virus, the gene at the centre of the current food row, but said he did own another GM patent on a product called a translator enhancer. All the interests had been placed in his blind trust.Reuse content