Cyber criminals are sending billions of spam emails mentioning swine flu to trick people into opening messages, experts have warned.
About 5% of all spam sent around the world now uses swine flu in the subject line, according to McAfee Avert Labs.
Of the 80 billion to 170 billion emails sent every day, up to 90% are spam, the internet security experts said.
The swine flu spam is being sent from all over the world from a network of compromised computers, with the majority coming from Brazil, the United States and Germany.
Spammers are using the virus to try to sell bogus pharmaceuticals or infect computers with malicious software.
Internet users were warned not to click on links embedded in the emails and to try to avoid opening the mail in the first place.
McAfee's director of security research, Dave Marcus, said: "Malware writers, spammers and scammers are low lives. They will use any high impact news story to push their wares.
"Should you need information on the flu situation, go to the World Health Organisation website or any reputable source, do not follow links that arrive in spam, instant messages or on social networking sites."
McAfee said it had also seen an increase in the registration of website domain names which mention swine flu, which could indicate a rise in malicious sites trying to take advantage of the scare.