More than half of the internet users on the continent are passive and do not contribute to the web at all, while a further 23% only respond when prompted. But the remainder who do engage with the net - through messageboards, websites and blogs - are helping change the national conversation, say researchers.

"We're seeing this growing," said Julian Smith, an online advertising analyst with Jupiter Research and author of the report. "The strongest part of their influence is on the media: if something online suddenly becomes a story in the local press, then it matters."

Although unprompted contributors are generally younger and more vocal than the wider online population, they are increasingly important as opinion formers and trend-setters. Mr Smith says businesses, media organisations and advertisers reading blogs should be wary of making assumptions about their wider significance, but that their muscle cannot be ignored.

"They're not representative of the larger audience, but what they're saying does matter," he said. "It's a good straw poll - a snapshot of the verbal conversations going on that we can't measure."

Mr Reynolds admits the idea of small groups being able to pressurise wider decisions is nothing new, but those who ignore online buzz do so at their peril: "You can bury your head in the sand, but very quickly you'll look like a very old-fashioned company."