The Office of Fair Trading has given games developers until 1st April to comply with what it calls “final principles for online and in-app games”.

The rules state that consumers must be made aware of future costs when they begin playing “freemium” games.

Parents have complained about children running up huge bills after upgrading from free games in order to advance or build a more powerful gaming position.

The announcement also covers the use of personal data and stipulates that parents or account holders must be informed before payment is made.

According to OFT: “Failure to comply with the principles could risk enforcement action.”

CEO Clive Maxwell added: “The on-line and apps based games industry has already made significant improvements during our consultation process. But it still needs to do more to protect children and treat its customers fairly.”