Nearly three-quarters of web users have left a favourite site because of intrusive or annoying ads, according to new research.

The annual Consumer Attitudes to Online Advertising study from HowTo.tv claims to have identified a growing resistance to badly-targeted online advertising, particularly among younger consumers.

The 25 to 34 year-old crowd are the least tolerant, 84 per cent of whom have abandoned a favourite online haunt at the sight of intrusive or irrelevant advertising, up 20 per cent on last year's survey.

Bugbears included ads with loud noises, pop-ups covering web content, and ads that were difficult to close, minimise or navigate away from.

The survey revealed that gambling sites, financial services companies, car companies and beauty brands were some of the worst offenders.

On the positive side, it seems that many surfers are engaging with online video. Around 70 per cent of respondents stated that they have watched an online video, but the impact of video ads varied widely depending on age.

When asked about the effect of a video ad on their favourite website, 56 per cent of 16 to 24 year-olds and 44 per cent of 25 to 34 year-olds said it would make them more likely to purchase the brand.

This compared to 38 per cent of 35 to 44 year-olds and 29 per cent of 45 to 54 year-olds.

"The survey highlights the urgent need for brands and media owners to rethink traditional approaches to online advertising," said Russell Goldsmith, co-founder and digital director at HowTo.tv.

"The difference in behaviour between younger and older web users shows that the mass audience model does not necessarily work in the online environment.

"It risks alienating web users and negatively impacting on their propensity to purchase."