The number of attempts to download illegal MP3s and software has increased by more than half over the last three months, according to ScanSafe, which regularly monitors network traffic on behalf of its clients. The data comes from network traffic monitored across more than 100 countries, ScanSafe said.

The company pointed to US student Joel Tenenbaum as the recipient of a $675 000 (£421,000) fine for illegal music downloads. The fine covered just 30 tracks, and amounted to $22 500 per song.

“Employees mistakenly assume they can use the internet at work in exactly the same way as they use it at home, and this is potentially one of the reasons for this steady increase in illegal download attempts over recent months,” said Spencer Parker, director of product management at ScanSafe. “Inappropriate internet use in the workplace can put the employer at risk for legal liabilities.”

He warned that employers can be held legally responsible for wrongful acts committed by employees on corporate networks. Even if the employer expressly forbids the action, it may still be held responsible under a principle known as ‘vicarious liability’, ScanSafe warned. It added that aside from the legal risk, corporate networks can be made vulnerable to malware from infected systems sharing software.

ScanSafe advised employers to create concrete policies defining allowable uses of the internet while at work. The policies should also outline the consequences of non-compliance, and staff should be made to acknowledge that they understand these rules.