Monsanto ads censured but safety claims backed LONDON, Aug 11 (Reuters) - Britain's advertising watchdog on Wednesday backed safety claims made in a newspaper campaign by Monsanto Co. but criticised the biotechnology giant for falsely suggesting its genetically modified potatoes and tomatoes had gained regulatory approval in 20 countries, including the UK. The Advertising Standards Authority (ASA) upheld four of 13 complaints made about the campaign, Britain's first consumer advertising for genetically modified foods. The series of seven ads which ran in national newspapers last summer, featured straplines such as ``Food Technology is a matter of opinions. Monsanto believes you should hear them all,'' and ``More biotechnology plants mean less industrial ones.'' The ASA received 81 complaints, including those from the Green Party, the Soil Association and members of the public. It ruled that Monsanto wrongly implied its GM potato seeds and tomatoes had been approved by regulatory agencies in 20 countries and it asked that future ads state clearly if specific crops have yet to gain approval in specific markets. But the ASA cleared Monsanto's claims that a switch from conventional crops to their GM equivalent could reduce pesticide use and land erosion, and improve water quality, mainly because the claims were expressed as an opinion. The watchdog said that although some experts were concerned about the toxicity of GM crops, it was satisfied that safety claims made by Monsanto for approved crops were in accord with accepted criteria in 20 countries. British press reports of ``Frankenstein'' foods have made genetically modified crops a controversial subject in Britain. Consumer fears have led major supermarket chains including Tesco and Sainsbury to begin removing GM ingredients from some of their product lines. The British government says carefully supervised GM crop trials will determine whether the modification of plants may lead to cheaper and tastier foods. Monsanto said the campaign had not been intended to mislead or deceive and changes had been made to ads during the campaign to comply with two of the upheld complaints. It said the ads featured contact numbers for environmental groups Friends of the Earth and Greenpeace, enabling consumers to hear both sides of the debate. ``We expected some criticism of the campaign as it was, and still is, the only attempt by any biotech company to explain the issues,'' Tony Combes, Monsanto's UK director of corporate affairs, told Reuters. He said the company had no current plans to advertise further in Britain. ASA spokesman Steve Ballinger said the non-broadcast watchdog's lengthy adjudication was not a judgment on the ethics of GM foods, but conceded that biotechnology firms were more likely to have pressure groups watching their campaigns closely than most other advertisers.