Just ten per cent of Twitter users generate more than 90 per cent of the content, a Harvard study of 300,000 users has found.

Estimates have suggested the micro-blogging platform now has more than ten million users and is growing faster than any other social network. But the Harvard researchers say more than half of those using Twitter updated their page less than once every 74 days . . . and most people only ever ‘tweet’ once during their lifetime.

Bill Heil, a graduate from Harvard Business School who carried out the work, said: “Based on the numbers, Twitter is certainly not a service where everyone who has seen it has instantly loved it. Twitter is a broadcast medium rather than an intimate conversation with friends. It looks like a few people are creating content for a few people to read and share.”

Recent figures from researcher Nielsen Online show that visitors to the Twitter website increased by 1,382 per cent – from 475,000 to seven million – in the 12 months to February 2009. It is now thought to have passed the ten million milestone.

By comparison, social networking site Facebook  has 200 million active users and grew by 228 per cent during the same period.

Nielsen also suggests that many people give the Twitter service a try, but rarely or never return – more than 60 per cent of US Twitter users failed to return the following month.

“The Harvard data says very, very few people tweet and the Nielsen data says very, very few people listen consistently,” Mr Heil told BBC News.