Facebook has established itself as the hottest hang-out spot on the web among Britons, overtaking MySpace as the most popular social networking site in the UK last month.

Facebook received 6.5 million unique visitors in August, compared to MySpace’s 6.4 million, according to Nielsen//NetRatings, the internet researchers. Both sites are now visited by one in every five Britons with online access, the numbers show, and are continuing to extend their reach.

The average Facebook user spent more than 16 hours on the site during August, compared with about nine hours for MySpace.

The news comes amid reports that Microsoft, the software giant, is pondering taking a 5 per cent stake in Facebook that could value the social network at $10 billion.

The site was founded by Mark Zuckerberg, 23, just three and a half years ago. It has since exploded in popularity among users and advertisers alike and is now exploring how to exploit the wealth of personal information - ranging from music tastes to religious leanings - that users plug into their profile pages.

It has also courted controversy, however, with concerns raised by users over privacy in the wake of a recent decision to make Facebook users' names and photographs accessible through search engines such as Google.

Since December, Facebook’s British audience has grown by 541 per cent, compared to 20 per cent for MySpace, which is owned by News Corporation, parent company of Times Online.

However, in a development that points to the fickleness of social network users, Facebook is no longer the fastest growing social network in the UK, according to NetRatings. That achievement now ascribed to Perfspot.com, which achieved 274,000 users last month.

Alex Burmaster, of NetRatings, said: “MySpace has managed to maintain more than six million visitors in each of the last six months – it will be interesting to see if Facebook can achieve this level of audience retention.”

MySpace, with some 200 million worldwide members still eclipses Facebook's total of 40 million users.

He added: “The suspicion that the next big thing in social networking could always be just round the corner is illustrated by PerfSpot. It wasn’t even on the social network radar until April of this year but in the last four months its visitor numbers have grown at a greater rate than Facebook has across the last eight months.”

There are also suggestions that the future of social networking will focus “on specific interest groups as opposed to the general behemoths that dominate today,” Mr Burmaster added.

“The fact that a number of the fastest-growing networks concern specific interest areas, such as business (LinkedIn), travel (WAYN) or music (Imeem), seems to add credibility to this theory,” he said.

The UK's most popular social networks

1. Facebook - 6,506,000 unique users in August - up 541 per cent since December

2. MySpace - 6,379,000 - up 20 per cent

3. Bebo - 4,449,000 - up 64 per cent

4. Windows Live Spaces - 2,333,000 - down 1 per cent

5. Friends Reunited - 2,112,000 - up 1 per cent

6. BBC Communities - 1,545,000 - up 27 per cent

7. Flickr - 1,276,000 - up 20 per cent

8. Piczo - 851,000 - down 40 per cent

9. Yahoo! Groups - 828,000 - down 1 per cent

10. WAYN - 669,000 - up 80 per cent

Fastest growing social networks

1. PerfSpot - up 756 per cent in the past year, with 274,000 users last month

2. Facebook - up 541 per cent, with 6,506,000 users

3. LinkedIn - up 194 per cent with 385,000 users

4. Orkut - up182 per cent with 175,000 users

5. WAYN - up 80 per cent with 669,000 users

6. Imeem - up 79 per cent with 125,000 users

7. Bebo - up64 per cent with 4,449,000 users

8. BBC Communities - up27 per cent with 1,545,000 users

9. Friendster - up 24 per cent, with 128,000 users

10. Tagged - up 24 per cent with 301,000 users

Source: Nielsen//NetRatings

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