A new forecast for the social network advertising market has been released by eMarketer.

According to the research company, worldwide spending on ads on social networks is likely to reach $2.35 billion (£1.64 billion) this year, up 17.3 per cent compared with 2008.

This will continue to rise over the next few years before reaching $3.49 billion in 2013, eMarketer predicted.

Debra Aho Williamson, senior analyst at eMarketer and author of the report, explained that the estimates are lower than previous forecasts made by her company.

Despite this, social network usage is still growing globally and a number of sites are finding new ways of generating revenues from their expanding user bases, she stated.

"Social network usage is growing substantially in many world regions, in several cases surpassing the usage levels seen in the US," Ms Williamson remarked.

She also said it is "good news" that spending is expected to rise by double-digit figures considering a number of firms have made single-digit forecasts for the wider ad industry this year.

More than two-thirds of the global online population visit social networking websites and blogs, according to a recent report from Nielsen Online.