Nine out of 10 people who click onto pop-up adverts are actually trying to close them down, new research has claimed.

The study found one award-winning Umbro advert that hit computer screens during Euro 2004 took users nearly a minute to close rather than the normal 2.5 seconds because they could not find the close button.

Umbro claimed 20% of users who saw the advert clicked onto the website. But Bunnyfoot Universality, the behavioural consultancy behind the study, found the real figure was more like 2% because the remaining 18% had actually been trying to close the ad down.

Rob Stevens, the head of business behaviour at Bunnyfoot, said trickery and confusing design in pop-up online ads was increasing, even though it angered users and damaged the brand.

"Lots of brands are doing it. They are not just wasting money, they are undoubtedly undermining the integrity of their brand," he said.

Mr Stevens called for the close button to be uniform and in the same position every time.

"The close button should be visible from the very beginning," he added.

Bunnyfoot had completed a study of websites of companies including BT, AOL, MSN and Wanadoo that found the effectiveness of online ads varied wildly.

The most prominent ad on the BT website was 36 times more likely to be seen than the ad in the worst position, the study, to be released shortly, showed.

It showed that the most expensive ad on the site, the banner ad near the top of the first page of the website, was the eighth most noticed.

Mr Stevens said the Internet Advertising Bureau, the trade association for interactive advertising, electronic commerce and online marketing, had not developed adequate audience measurement devices.

"It's still a bit of the wild west, to be truthful," he said.

Bunnyfoot came to its conclusions after studying the behaviour of 60 people.

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