A composite image shows some of the billions of profiles on Facebook.
Facebook was investigating a cyber attack Friday which saw personal details from 250,000 of its members posted on a new dating site without permission.
Dating site Lovely-Faces.com launched this week with the names, locations and photographs, all taken from the pages of unsuspecting Facebook users.
Cyber pranksters Paolo Cirio, a media artist, and Alessandro Ludovic, media critic and editor in chief of Neural magazine, were behind the rogue dating site, which could lead to hundreds of thousands of unwanted advances.
The pair told tech blog Wired in a statement they wanted to reveal the gaps in Facebook's security settings and undermine its $50 billion valuation, which was set after Goldman Sachs invested in the company last month.
"Facebook, an endlessly cool place for so many people, becomes at the same time a goldmine for identity theft and dating -- unfortunately, without the user's control. But that's the very nature of Facebook and social media in general. If we start to play with the concepts of identity theft and dating, we should be able to unveil how fragile a virtual identity given to a proprietary platform can be," the statement said.
Facebook spokesman Barry Schnitt said the site was looking into the profile thefts.
"Scraping people's information violates our terms," he said. "We have taken, and will continue to take, aggressive legal action against organizations that violate these terms."
The Lovely-Faces.com website was "temporarily unavailable" Friday.
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