Facebook? Better to tweet your friends...

It could be the new Facebook and already has millions of fans, from Gordon Brown to Barack Obama.

Twitter is a free website which allows people to send 140-character messages, known as tweets, to groups of friends.

Today, it revealed an increase in visitors of more than 600 per cent in the past year, with more than three million messages sent every day.

Several million people have registered for the service and the company says 10 per cent of its traffic now comes from Britain.

Founded by Americans Evan Williams, Biz Stone and Jack Dorsey, the San Francisco-based site was credited with breaking the news of the Chinese earthquake in May when users there sent messages about the disaster through the service.

"It's incredibly useful for keeping tabs on incoming stories," said Tom Watson MP, a parliamentary secretary at the Cabinet Office whose brief includes technology. "Number 10 now uses it, as does Hazel Blears. It's a very good way for us to address niche audiences and to distribute data succinctly. It's also useful for gauging people's reactions as you can see the amount of responses people get." In the UK, twitter has grown by 485 per cent so far this year and 631 per cent year-onyear. However, the service has suffered technical problems due to its growth and users are used to seeing the "fail-whale", a graphic of a whale displayed when the system crashes.

Robin Goad of Hitwise, which monitors internet traffic, said: "It began with early adopters but it is definitely getting more mass market.

"I don't think it will replace Facebook but will run alongside it - your twitter feed can be your Facebook status update, for example. I think what is attracting people are the more unusual users - the BBC posts its headlines. It can be very compelling."