Phone numbers of as many as 400 million Facebook users have been leaked, news agency AFP quoted the US media as saying. According to technology news site TechCruch, an exposed server stored 419 million records on users across several databases - including 133 million US accounts, more than 50 million in Vietnam, and 18 million in Britain.
Facebook user IDs - unique digits attached to each account - the profiles' phone numbers, gender, geographical locations of some Facebook accounts were listed in the databases.
The databases could be accessed by anyone since the server was not password protected.
While Facebook confirmed parts of the report, it also downplayed the extent of the exposure. The social media giant said that the number of accounts so far confirmed was around half of the reported 419 million. Many of the entries were duplicates and the data was old, it said.
"The dataset has been taken down and we have seen no evidence that Facebook accounts were compromised," a Facebook spokesperson told AFP.