Tired of social networking? Logging off Facebook? You're probably not the only one.

Fearing for their privacy or perhaps just bored with using the site, 100,000 Britons are said to have deactivated their accounts last month.

And Facebookfatigue seems to be catching. Six million logged off for good in the US too, figures show.

Worldwide, the rate of growth has slowed for a second month in a row - and as it aims to reach its goal of one billion active users, Facebook is having to rely on developing countries to boost its numbers.

The figures suggest that there could be a 'natural limit' for Facebook's saturation.

There is even speculation on blogs that, as is feared for its failing rival MySpace, the website could one day 'sputter into oblivion'.

Earlier this year, executives announced that the number of Facebook accounts held in the UK had reached 30million, accounting for about half the population.

The milestone was an increase of four million from last July and represented the highest saturation of any country in Europe.

But times change - and last month more than 100,000 in the UK stopped using the website, figures show. In the U.S, user numbers dropped from 155.2million to 149.4 million throughout May. In Canada there was also a fall, of about 1.5million users, while in Russia and Norway numbers also fell by more than 100,000 users.

It's not all bad news for the site. Worldwide, Facebook is still expanding and has around 600million users, thanks to strong growth in countries such as Mexico and Brazil.

According to Eric Eldon, of the website Inside Facebook, which obtained the figures through analysis of the company's advertising tools, there is a point at which the site can no longer grow, once it has established itself in a country.

'By the time Facebook reaches around 50 per cent of the total population in a given country, growth generally slows to a halt,' he explained.

(Read by Renee Haines. Renee Haines is a journalist at the China Daily Website.)