A page from the Facebook website is seen in Singapore May 11, 2011. Facebook users' personal information could have been accidentally leaked to third parties, in particular advertisers, over the past few years, according to Symantec Corp's official web blog. Third-parties would have had access to personal information such as profiles, photographs and chat, and could have had the ability to post messages, the web blog said. REUTERS/Tan Shung Sin (SINGAPORE - Tags: BUSINESS SOCIETY SCI TECH)