Internet monitoring company comScore has unveiled the June results of its World Metrix audience measurement service, and although the top visited sites remain largely unchanged, emerging sites are starting to nip at the heels of the established stalwarts.

The company registered a record 31.7 million unique UK visitors to the internet in June, representing 63 per cent of the total UK population age 15 and older. The average internet user in the UK spent almost 35 hours online during the month.

The results show that we continue to return to our old favourites time and time again, with Google holding its spot as the most visited property in the UK with 27.7 million unique visitors in June, reaching 88 per cent of the total UK online population.

Similarly, Microsoft and eBay remained the second and third most visited properties in the UK, with 26.8 million and 22.1 million unique visitors respectively.

"With Google and Microsoft each reaching more than 85 percent of the UK online audience, it's fair to say that they have established a large online footprint," said Bob Ivins, executive vice president of international markets at comScore.

"However, their leadership position in the UK is not without competition, as sites are emerging all the time – Facebook being the prime current example – helping ensure that the larger players are kept on their toes and are spurred to continue to innovate."

That most of the top twenty most visited properties incurred only modest changes in visitation levels from the previous month indicates that these sites, while well established, run the risk of stagnating and being overtaken by the popular up and comers.

Although Adobe saw its traffic swell by 11 per cent in June, this can be considered an isolated incident attributed to the release of an Acrobat Reader update.

More noticeably, social networking site Bebo was the second biggest growing property in the top twenty, with its traffic increasing by seven per cent.

Overall, the fastest growing property in June was Mozilla with 41 per cent more unique visitors than in May, driven by the continued uptake of Firefox.

The Channel 4 site also saw a huge increase in traffic with a 39 per cent increase in unique visitors, reflecting the massive increasing interest in web TV.

Another social networking site, Facebook, was third on the list of top gainers in June, growing a further 25 per cent. At its current rate Facebook will enter the top 20 most visited sites in the UK in July and begin to give the top placeholders a real run for their money before the end of the year.

While the big search engines will always maintain a strong position, comScore's latest figures reflect the growing use of the internet as a multimedia and social hub, with more and more UK surfers accessing the web for all their needs including information, entertainment and networking.