The European Commission is pushing Google and Apple to police game apps billed as “free,” but end up being costly to parents who are billed for in-app extras when their kids play them.

The EU regulator’s action, announced Friday, July 18, joins similar action seen in the U.S. The Federal Trade Commission in January. In that case, Apple agreed to repay $32.5 million to parents whose children racked up charges without their consent, according to report in the UK Telegraph.

Google, for its part, has announced it would stop labeling games “free” when they in fact could lead to in-app charges.

Apple however, has not responded adequately to the Commission’s concerns, prompting it to issue a terse statement on Friday, saying it was working with individual EU governments to address this problem. This not only amounts to added pressure on Apple, but could lead to prosecution.

“Although regrettably, no concrete and immediate solutions have been made by Apple  to address the concerns linked in particular to payment authorization, Apple has proposed to address those concerns,” the statement reads. “However, no firm commitment and no timing have been provided for the implementation of such possible future changes.”

According to data provided by the Commission, The Telegraph reported Europe’s burgeoning app market will top €63 billion within five years, with users in top EU economies Britain, Germany France, Italy, Spain, the Netherlands and Belgium spending €16.5 billion as recently as 2011. More than half of the online games in the EU are advertised as “free” but carry hidden costs.

Apple may face legal action if it does not comply with the Commission’s directive. The British newspaper gave as an example an 8-year-old girl who racked up £4,000 in charges to her father’s credit card while playing My Horse and Smurfs’ Village. Apple issued a full refund in that case.