Facebook may be at a saturation point in the UK, according to new statistics released by online research firm Hitwise on Tuesday.

Although more than 25 million Britons, or one in three of the entire population, now have a Facebook account, the average time spent on the social networking site has decreased, the report added. From 30 minutes in December 2009, it has come down to 27.36 minutes during June and July 2010.

The data reveals that Facebook is still the second most visited site in the UK and that it accounts for one in every six web pages accessed.

The site's market share of UK page views has trebled over the last five years, although growth has slowed significantly over the last six months, Hitwise's research director Robin Goad said.

"Facebook has a very high average session time - almost half an hour - but this has also stabilised over the last six months after increasing rapidly during the site's ascendancy," added Goad.