Over 7.5 million Britons visited online games sites during June, according to a report by Nielsen/Net Ratings.

The research group says the UK’s online gaming audience has grown 16% in the last year, largely thanks to demand from teenagers, with Miniclip being the most popular site.

It is generating 1.3 million unique visitors per month, but isn’t the stickiest brand – that position is held by fantasy adventure game RuneScape, whose visitors’ average two hours and 25 minutes of monthly playing time.

Runescape and Miniclip are also the two brands on the web with the greatest percentage of under 18 year old visitors, the report says.

According to Nielsen/NetRatings, a third of the online games audience is under 18, compared to 20% for the entire web.

But apparently, 6.4% of the online games audience is made up of women over 50 (is it me or does that seem like quite a lot?).

Overall, 28% of Britons online (7.6 million) visited online games sites in June. Competition is also hotting up as the big players invest in the sector.

MTV Networks’, for example, announced earlier this month that it plans to spend US$200 million on Atom Entertainment, the owner of games portal Shockwave and AddictingGames, after splashing out on a series of other web games providers.

Alex Burmaster, European internet analyst, Nielsen/NetRatings, said: “Take the fact that the online games sector is growing at four times the rate of overall Internet growth together with the increasing numbers of under 18 year olds online and it is easy to see why companies such as MTV Networks are looking to get a piece of the action.”