A security researcher has offered to donate £500 to charity if a dating website that was supposedly the victim of a virus sends the malware to him, or another antivirus firm, for analysis.

Dating site BeautifulPeople.com, which requires members to vote on whether new users are good looking before they are given access to the site, claimed it had been attacked by a virus that removed this process, allowing thousands of new web users to join the site without passing the attractiveness test.

The site then reviewed the users and decided they were too 'ugly' for the site and revoked their membership. The site even went as far as to nickname the virus 'Shrek' after the animated tale about an ogre who learns that looks don't matter.

However, Graham Cluley from security firm Sophos quickly branded the incident a clever PR stunt.

"It's a fantastic piece of chicanery, of course, designed to boost awareness of the dating website, get them many thousands of pounds of free publicity with little risk of damage to their reputation," said Cluley in a blog.

According to Cluley, the website explains that it doesn't need to inform any computer security firms about the malware as it is being "investigated internally", that a "former employee placed the virus before leaving the team" and "despite wreaking havoc with the application process, member privacy and security was never breached".

"My bet is that BeautifulPeople has just come up with its latest publicity stunt - and you know what? It's worked," he added.

Now Cluely has gone one step further, using micro-blogging site Twitter to challenge the dating site to hand over the so-called virus.

"If Beautiful People forward the Shrek virus to an antivirus firm for analysis I'll give 500 quid to Children in Need," Cluley said in a tweet.

BeautifulPeople.com has yet to respond.