Antivirus experts are predicting that Instant Messaging will become an increasingly popular way to spread computer viruses, and warned companies that they face more of the same dangers that struck during the first half of last year.

"The public is still very gullible and fall for the temptations that virus writers send them," said Jack Clark, marketing manager for antivirus specialist McAfee. "Companies simply must take the initiative, because their staff may not. This means we will see an increased use of content scanning and blocking technologies this year."

Clark also said that he foresees more security firms offering managed services this year in the ongoing battle against virus authors.

Kaspersky Labs, a Moscow-based security company, said that antivirus firms had achieved many successes against virus proliferation last year, but that 2001 had also seen an increase in the number of users who suffered from virus attacks.

Kaspersky blamed the easy spread of viruses largely on users that have "only a superficial understanding of proper computer safety guidelines and rules".

The company expects an increase in the number and sophistication of messenger and shared file programmes such as Gnutella to spread viruses, more malicious programmes for Linux, and Windows network worms.

Last month saw the highest virus activity ever recorded, according to security specialist Central Command. The Goner virus led the charge, accounting for 37 per cent of all virus reports, followed by BadTrans.B (27 per cent), Nimda (7.5 per cent) and Sircam (six per cent).