The video download, which may claim to contain hidden camera footage of you, or a famous celebrity, then encourages you to download an updated version of the Adobe Flash Player plug-in. Other newly emerging threats include fake Facebook alerts from malicious third-party applications that say your friends are having trouble viewing your profile or have reported you for a violation of the company's terms of service. Notification messages typically read: "Error Check System" or "F a c e b o o k - closing down!!!"

Whoever clicks on these inadvertently sends the same notification to everyone on their friends list, replicating the malware and opening access to all of their personal profile data. "A major motive for this type of attack is to give a person third party access to your computer. Primary infection is generally not what causes the damage," said Adam Biviano, a spokesman for security software company Trend Micro. No stranger to Facebook malware is PR manager, Caroline Simpson, whose computer was infected with the Koobface worm in December after clicking on a video link sent from a colleague in the US.

"It told me I needed to update my Adobe Flash to see the video, but no video came up. I clicked it again and then closed down the computer. When I opened up the computer later that day I wasn't able to access any files. A pop-up said I had downloaded a virus and offered to sell me a package to remove it. "We wasted about half a day or more removing the malware after trawling through the web and Facebook looking for instructions on how to get rid of it". Thousands of Facebook users have flocked to groups on the website dedicated to viruses and other malware, some just issuing warnings, others who learned about the threat the hard way.

"Just got my computer back today from Computer Depot and they said I had a very bad virus from Facebook, it just about killed my system completely...so please be aware," said one user. "I have the virus on my laptop, and I cant open up ANY programs sensibly or do anything really...all these virus scanners that come with the virus go crazy when I turn on my computer," said another. Although Facebook disables malware applications reported by users, it maintains a hands off policy when it comes to approving applications uploaded to its website.

"We've tried to make the process of building on the Facebook Platform relatively easy in order to stimulate innovation - and to allow the kid in a college dorm room to compete against the big corporation. ". . .our developer community has more than 660,000 developers . . . The drastic measures others have suggested is akin to saying, 'there have been two robberies, we need to implement martial law in the city'," the company said.

"Graham Cluley, a senior technology consultant at security company Sophos said that while it was impractical to expect Facebook to check every single application that users upload, that didn't mean it should do nothing. "The first thing would be that anyone wanting to write a Facebook application would have to prove their identity and contact details. "My proposal would be that Facebook application developers would need to jump through several hoops before they were approved to unleash their applications on the networks' 150 million plus users."