The Storm worm is trying a new tactic to lure users by hiding its malware within a fake news story about the FBI and Facebook.

Spam messages contain such headlines as 'FBI may strike Facebook', 'FBI are spying on your Facebook profiles' and 'Facebook's FBI ties'.

On attempting to view the supposed video of the article, the user is presented with an executable file which ads the PC to the Storm botnet.

Researchers at security firm Sophos first discovered the spam run early yesterday and said that this is the third campaign from Storm within a week.

The other attacks include fake stories on a new North American currency known as the 'amero' and a run of fake greeting cards.

The attacks are very similar to another spam run earlier this month in which users were tempted with fake stories about the US invading Iran.

The US Computer Emergency Response Team is encouraging users to avoid opening suspicious email attachments and to keep antivirus software updated.