The European commission (EC) has praised Google but criticised Apple over the steps both companies are taking to ensure children don't spend money on in-app purchases (IAP) without their parents' permission.

The EC has been working with consumer protection bodies in its member states, as well as app store owners, to improve their policies following controversies and concerns around the use of IAP in apps and games played by children.

The commission has set out rules for the app store owners to follow, including not advertising games as "free" and misleading people about the true costs; and banning "direct exhortation to children to buy items in a game or to persuade an adult to buy items for them".

It has also demanded that in-app purchases should not be made "through default settings without consumers' explicit consent", and insisted that apps firms provide email addresses so that they can be contacted with queries and complaints.

A statement released by the commission praised Google for a series of changes that will be put in place by the end of September.

"These include not using the word "free" at all when games contain in-app purchases, developing targeted guidelines for its app developers to prevent direct exhortation to children as defined under EU law and time-framed measures to help monitor apparent breaches of EU consumer laws. It has also adapted its default settings, so that payments are authorised prior to every in-app purchase, unless the consumer actively chooses to modify these settings."

Apple, meanwhile, is on the end of some sharp words from the commission over its response since the new rules were communicated at the end of 2013:

"Although, regrettably, no concrete and immediate solutions have been made by Apple to date to address the concerns linked in particular to payment authorisation, Apple has proposed to address those concerns. However, no firm commitment and no timing have been provided for the implementation of such possible future changes. CPC authorities will continue to engage with Apple to ensure that it provides specific details of changes required and put its practices into line with the common position."

Apple has lost no time in responding to the criticism with a statement outlining its efforts to prevent IAP abuse – particularly relating to children – in its App Store.

"Apple takes great pride in leading the industry in parental controls that are incredibly easy to use and help ensure a great experience for parents and children on the App Store," a spokesperson told the Guardian.

"The parental controls in iOS are strong, intuitive and customisable. And over the last year we made sure any app which enables customers to make in-app purchases is clearly marked. We’ve also created a Kids Section on the App Store with even stronger protections to cover apps designed for children younger than 13."

The spokesperson added that "these controls go far beyond the features of others in the industry" – a clear reference to Google, as well as rival app stores from companies like Amazon, which is being sued by US regulator the Federal Trade Commission over "millions of dollars in unauthorized in-app charges incurred by children" on its Android store.

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The European commission is leaving enforcement, including legal action, in the hands of national authorities in its member states. The UK's Office of Fair Trading has been investigating the issue since 2013, including publishing a report outlining best practice for app developers.

Earning the trust of parents over in-app purchases is becoming one of the battlegrounds between Apple and Google with their respective app stores and device software.

In June, Apple unveiled the next big software update for iPhones and iPads, iOS 8. Due to be released later this year, it will include a feature called Ask To Buy, which will require children to get permission from parents before making any purchase on their device.

Apple has also launched a series of parental guides to in-app purchases and the settings to restrict them, as well as a feature called iTunes Store Allowance for parents to automatically credit a child's account with money once a month, to manage their spending.

However, in January 2014, Apple also agreed to pay at least $32.5m to consumers to settle its own Federal Trade Commission complaint about children and in-app purchases, providing a full refund to affected parents after the FTC reported "at least tens of thousands of complaints" over iOS apps.

The puzzling aspect to the EC's specific criticism of Apple – "no firm commitment and no timing" to addressing payment authorisation issues – is that Ask To Buy appears to be exactly that, even if the launch of iOS 8 remains pegged as "autumn" rather than a specific date.

With Google praised for promising to put in place some measures already implemented by Apple, the latter is likely to be feeling hard done by over the EC's criticism. However, European politicians are resolute in their determination to keep up the pressure on both companies.

"The commission is very supportive of innovation in the app sector," said vice president Neelie Kroes. "In-app purchases are a legitimate business model, but it's essential for app-makers to understand and respect EU law while they develop these new business models."

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