Biotech crops giant Monsanto has been ordered to withdraw an advertising claim that no negative reactions have ever been reported to genetically modified foods.

The Advertising Standards Authority made the ruling this week in response to a consumer complaint lodged against a Monsanto South Africa print ad referring to GM grain products.

The ASA added however that it would reconsider its ruling if Monsanto came up with substantiation of its claim.

The ad, which ran in the February edition of You magazine, carried the heading: "Is your food SAFE?" and contained an image of a woman with two children in a kitchen looking at a cake.

Below the sub-heading: "Biotechnology - the true facts" it said: "This is one of the most extensively tested and controlled types of food, and no negative reactions have ever been reported."

The ASA said the complainant, a Mark Lewis, said the "no negative reactions" claim was false, and cited a scientific study on "the dangerous effects of these products".

Monsanto had said in response that all biotech crops approved for commercialisation world-wide had been thoroughly assessed for safety according to international guidelines.

They had been found to be as wholesome, nutritious and safe as conventional crops, Monsanto said.

The ASA said, however, that the onus was on Monsanto to provide independent verification of the "no negative reactions" claim.

Though Monsanto had provided numerous studies contradicting claims that GM foods were unsafe, they made no reference to the "no negative reactions" claim in the ad.

The claim was therefore "currently unsubstantiated", the ASA said, and had to be withdrawn immediately.

The claim could not be used again in its current format until substantiation had been submitted, evaluated, and a new ruling made. - Sapa