The FBI's Internet Crime Complaint Center is warning of three email scams in wide circulation. 

The first is a letter claiming to be from the FBI, bearing the seal of the organisation and a picture of director Robert S. Mueller III. The email claims that the recipient has won money in a lottery.

The second purports to come from the US Army mailing system and attempts to harvest personal and financial information from the recipient. The email claims that the information will be used to help the armed forces overseas.

The third is a variation of a common scam in which the email claims that an electronic greetings card has been sent. Once the link is clicked on the user is directed to a web page harbouring malicious code.

"These spam email messages are hoaxes and should be immediately deleted," said the FBI in a statement.

"Consumers need to be wary of unsolicited emails that request them to take any action even if that means just clicking on an attachment.

"It is possible that by double-clicking on attachments to these messages, recipients will cause malicious software, e.g. viruses, keystroke loggers or other Trojans, to be launched on their computers."

The Internet Crime Complaint Center was set up by the FBI and the National White Collar Crime Center to combat the growing problem of internet fraud and computer viruses.