Facebook engaged in practices that "tricked" children and their parents into spending money in free-to-play games, the media has reported.

According to records that are part of a class-action lawsuit, and include internal Facebook memos, secret strategies and employee emails, the social media giant engaged in what was internally dubbed "friendly fraud" in order to maximise its revenues.

"And the company often denied attempts by parents to recover hundreds or even thousands of dollars until credit card companies 'clawed back' the money from Facebook," the VentureBeat reported late on Saturday.

The story detailed the case of one 12-year-old boy who had spent nearly $1,000 in the game Ninja Saga. That case led to a lawsuit in 2012, the report added.

The time span for the abuses covered 2010 to 2014, but the documents related to these cases were not released until now.

An internal Facebook survey of users found that many parents did not even realise that the social networking giant was storing their credit card information.

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And parents also did not know their children could use their credit card without re-entering a password or some other form of verification, according to the Reveal. (IANS)