One in 600 profile pages on social networks host some form of malware, a new study has found.

Research by security firm ScanSafe analysed over five billion web requests in July.

Traffic to social networking sites – such as MySpace and Bebo – thought to be popular with teens, accounted for one per cent of all web use in the workplace, the company found.

"Social networking sites have been newsworthy because of the concern over our children’s safety," said Eldar Tuvey, CEO and co-founder, ScanSafe. But he warned that such sites could expose people to harmful software as well.

"Users are frequently subject to unwanted spyware and adware that can compromise their PCs, track online behaviour and degrade PC performance," Tuvey said.

Closed social networks, such as Facebook, which requires users to have a university email address or business networking site LinkedIn, were less susceptible to infection than open networks. No malware at all was found on LinkedIn.

ScanSafe also discovered referrals to adult personal sites, such as adultfriendfinder.com on social networks popular with teens.

"The presence of adult-oriented adware is disturbing, not only because much of it is inappropriate content for minors, but because underage users may not be in a position to consent to installing adware or understand the end-user licence agreement," Tuvey said.

During July, the research found that on the whole the volume of spyware increased by 19 per cent, while web viruses decreased by 14 per cent.