The Advertising Standards Authority has upheld complaints from environmental groups about a series of newspaper advertisements used by Monsanto to calm public fears over the safety of GM foods.
The complaints are part of a growing trend where the ASA finds itself adjudicating on politically sensitive claims between activist groups and commercial companies.
The adverts claimed that "rigorous tests have been undertaken throughout Monsanto's 20-year biotech history to ensure our food crops are as safe and nutritious as the standard alternatives".
The ASA took expert advice from scientists and discovered that before 1983 Monsanto's research was centred on developing GM techniques and did not include evaluation of their effects on humans and the environment. A spokesman for the ASA said: "When Monsanto clearly state what its beliefs are we do not have a problem with it. But the complaints we upheld were about factual statements that were made.
"A big company like this knows there are pressure groups out there who will pick holes in everything it says and should be very careful with their advertising."
The ASA dealt with complaints from the public and environmental groups such as the Soil Association and the Royal Society for the Protection of Birds against 13 adverts. In all, the regulator upheld four complaints and dismissed the rest.
Among those upheld were complaints about an advert by pro-hunt group Countryside Alliance. It was found to have used "misleading and inaccurate comments" in an advert that aimed to tell the truth about country sports. The judgment said that some of the statements made by the Countryside Alliance were "misleading", that it had misquoted from a previous ASA report and it said the Alliance should "take more care in future" with its adverts.
In another instance of a campaigning group prompting an investigation, the ASA spent three years looking into claims made by Nestle in an advert in a student newspaper about its supplies of formula milk to the developing world. Baby Milk Action, which made the complaints, was rewarded with an adjudication which allowed them a victory over Nestle.
Individuals with concerns about the regulation of the cosmetic surgery industry have also used the ASA to attack companies they believe to be misleading the public and breaking the regulations about their surgeons' qualifications.
Complaints to the ASA by a few dedicated individuals have led the Government to consider tightening up the regulation of clinics offering cosmetic surgery.