Facebook has admitted that some of the most popular applications on its site have been passing on user data, in the latest privacy breach to hit the social networking site.
Popular apps such as FarmVille, Texas HoldEm Poker and FrontierVille have been providing users' details to advertising and internet tracking sites, according to a report in The Wall Street Journal.
Facebook User ID is a public part of any Facebook profile, and anyone can use an ID number to look up a person's name using a standard web browser, even if that person has set all of their Facebook information to be private.
All of the 10 most popular apps were found to be transmitting User IDs, while the top three, including FarmVille, are also making personal information about a user's friends available to outside companies.
The apps reviewed by The Wall Street Journal had sent Facebook User ID numbers to at least 25 advertising and data firms, several of which build profiles of internet users by tracking their online activities.
Facebook acknowledged the breach in a blog post, but still maintained that it takes privacy seriously.
"Recently, it has come to our attention that several applications built on Facebook Platform were passing the User ID, an identifier that we use within our APIs, in a manner that violated this policy," the post said.
"In most cases, developers did not intend to pass this information, but did so because of the technical details of how browsers work."
The post also claimed that reports have been exaggerated, and that " knowledge of a User ID does not enable private information to be accessed without explicit user consent".
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago