"The spam that attempts to smash its way into users' e-mail accounts can vary from being annoying adverts to downright malicious attacks. In the worst cases, a spam message might be designed to infect your computer with a Trojan horse or phish your banking credentials," said Graham Cluley, senior technology consultant, Sophos. "These latest statistics suggest that, as more people get online in Asia, they are not taking the right measures to protect their computers from infection, which results in the growth of botnets."

Sophos said the majority of spam e-mails are distributed by botnets -- networks of infected machines, called zombie computers, which are under the control of spammers. Botnets are also used to launch Distributed Denial of Service attacks (DDoS), where thousands of zombie computers are used to connect to a website, forcing it offline as it struggles to cope with the increase in traffic.

Computers risk being victimised by botnets if these computers don't run up-to-date antivirus software and security patches, said Sophos.

"If you receive spam messages, check any filter settings you may have and make sure your security software is running and has the latest patches installed," said Cluley. "Don't ever be tempted to buy anything via spam, as that's what makes it worthwhile for the spammers. Don't even open unsolicited e-mails as that alone could lead to malware infection -- send them straight to the trash."