The findings are part of the Advertising Standards Authority's Internet Banner and Pop-up Advertisements Survey published today, the first by the body that oversees non-broadcast marketing communications.
It looked at 357 banner ads and 264 pop-ups on a selection of UK websites between July 1 and December 31 2002.
The MG ZR ad for MG Rover was the only one surveyed during that period deemed to be in breach of ASA codes. It had already had complaints about it upheld in other media, because it associated speed with the car.
A further 37 ads were deemed to be "questionable" by researchers. The ASA said that the majority of these were for betting and gaming websites and appeared on sites that were likely to appeal to under-18s. If questionable ads are included in the survey, the compliance rate falls to 94%.
Danny Meadows-Klue, chief executive officer of the Interactive Advertising Bureau, said: "This survey reflects positively on our industry's commitment to self-regulation.
"While we are confident that this will give the industry the confidence to accelerate this market faster, we can not afford to rest on our laurels. In order for the high standards to continue into the future, we must carry on complying with the industry's own code."
The ASA survey says that banner and pop-up ad messages tend to be simple and do not try to convey the same amount of information as many print ads do. It is often claims that can not be properly substantiated which land advertisers in trouble for breaching the ad codes.
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