Organised crime is moving online into spam and virus writing - which means attacks may become less common but more dangerous, a Russian antivirus expert has warned.

As criminal gangs get involved, the 'independent' operators that currently dominate the spam and virus market will be squeezed out, reducing the total number of attacks.

The latest MiMail worms were the first in a new type of attack aimed at deriving financial profit from viruses and malware, according to Eugene Kaspersky, co-founder of Kaspersky Lab and head of its antivirus research.

Recent MiMail variants collected and forwarded PayPal account details to the worms' creators.

"The business of the mafia is business, and there could be a lot of money to be made from malware and spamming," said Kaspersky.

"As they consolidate control of the business of hacking and virus writing they will squeeze out independents. Spam will be an early target.

"If you are a spammer or malware developer, sooner or later the mafia will come knocking on your door."

Although overall virus attacks might decline, targeted viruses could be used to steal commercial valuable secrets or bring down networks, Kaspersky added.

To combat these kinds of threats a new set of internet protocols would need to be designed with security in mind.

"Spam is ripe for organised crime, as the majority of spam relates to the vice and drugs industry," said Professor Neil Barrett, technical director at Information Risk Management.

"The only downside is that spam isn't that effective as a marketing tactic so may not be a money-spinner.

"I'm not sure I agree on viruses, since they are untargeted and not very efficient. But the capability to launch denial of service attacks for extortion fits perfectly with the mafia business model."