By Nick Allen, PA News

Four leading supermarkets launched investigations today after tests commissioned by Friends of the Earth detected banned genetically modified maize in the stores' own-brand tortilla chips.

The pressure group took a total of 20 foods from British supermarket shelves and sent them to a laboratory in Germany to be analysed for types of GM maize which cannot legally be sold in Europe.

The tests found GA21 `Roundup Ready' maize, which is manufactured by the biotechnology giant Monsanto, in three products including Safeway's and Asda's own-brand tortilla chips, said Friends of the Earth.

Traces of another GM maize DBT418, which is made by the Monsanto-owned company Dekalb, were found in own-brand tortilla chips sold by Sainsbury's and Tesco, the pressure group said.

Both maizes, which have been genetically modified to boost their resistance to herbicides, are grown and sold in the United States but are not approved in the UK.

Earlier this year the UK's Advisory Committee on Novel Foods and Processes decided Monsanto had not provided sufficient information on whether GA21 could lead to allergic reactions.

And there have been concerns raised over whether DBT418 could have an impact on the effects of antibiotics.

Friends of the Earth called for better traceabiilty to stop unapproved GM ingredients sneaking on to British supermarket shelves.

The four supermarkets, who all say their own-brand products are GM-free, said they would investigate the findings but none removed their tortilla chips from sale immediately.

A Safeway spokeswoman said: "We are investigating thoroughly. We took the decision to take out all GM ingredients from our own-brand products a while ago and that was successfully completed earlier in the year."

An Asda spokeswoman said: "In October 1998 we asked our suppliers to stop using GM ingredients in our own-label products.

"Since then we have carried out regular and independent testing to ensure that they are genuinely free of GM ingredients.

"But we will obviously be investigating this matter further."

A Sainsbury's spokesman said: "We take this very seriously. Due to consumer demand Sainsbury's eliminated all GM ingredients from all its own-brand products, which involved 4,000 lines."

The supermarket would be "taking immediate action to investigate this
finding".

A Tesco spokesman said: "We don't use GM ingredients in our own products.

"We are going to conduct an investigation and we will be looking at the methodology and results of these tests and will carry out our own tests.

"If there is an issue we will talk to the suppliers to solve it."

A Friends of the Earth spokesman said: "We think they should remove these products from the shelves because it is illegal to sell them and we think there should be a much stricter testing regime.

"Why is it down to a pressure group like us to do these tests, where is the Government on this?

"The Government must learn the lessons of BSE and ensure that our food is protected from illegal ingredients.

"This means setting up effective testing systems and making GM firms legally liable if things go wrong.

"If the biotech industry cannot guarantee segregation and traceability they shouldn't be allowed to import their products into the UK."

The tests also detected Roundup Ready maize in Phileas Fogg Authentic tortilla chips and traces of DBT418 in Phileas Fogg Nacho Cheese tortilla chips, said Friends of the Earth.

A spokesman for United Biscuits, which owns Phileas Fogg, said it would investigate but was confident the products were GM-free.

"We have a very robust testing programme and have been GM-free for three years," said a spokesman.