This year will see a dramatic rise in phishing attacks and a plague of viruses written for spammers, security watchers have warned.

Security appliance manufacturer Fortinet reported a big increase in phishing during 2004 which is expected to increase this year. Meanwhile, viruses written specifically for criminals are predicted to reach epidemic proportions.

"There are most definitely wolves in the virtual den," the Fortinet report stated. "They become wilier with each new email that attempts to massage personal banking information from the unsuspecting user."

The company also highlighted speculation that spammers are hiring virus writers to create networks of slave PCs, so-called botnets, that send out email without their owners' knowledge or consent. Police have suggested that these botnets are being traded on the open market.

Last year also an increase in virus toolkits. The Agobot virus, the code for which is freely available on the internet, now has over 1,500 variants due to people customising their own versions.