Bloggers are playing an increased role in influencing what people buy - damaging the way traditional marketing is done over the Internet.

According to a report from Jupiter Research, most European internet users do not input online, but blogging 'by a vocal minority' has a disproportionately wide influence.

In its report called Consumer Created Content: Assessing the Influence of Content-Contributing Online Consumers, the firm maintains that 53 per cent of visitors to online publishing sites are passive, silent surfers who do not respond to polls or competitions; 24 per cent said they regularly maintain or contribute to weblogs, websites or forums.

The report warns that marketers need to be aware of just how influential the opinions of certain blogs are and how fast they can circulate in the blogosphere.

'With the adoption of content-creation tools democratising the publishing of information, consumers will increasingly be exposed to informal, peer-produced content alongside formal, professionally created content,' stated report author Julian Smith.

'As the quantity of postings grows, organisations must pay increasingly close attention to this online contribution.'