Britain’s competition regulator is inverstigating the power of Facebook and Google in digital advertising markets, including the ownership of data.

The Competition and Markets Authority (CMA) will examine the major online platforms such as Facebook and Google which are funded by digital advertising. It will consider the sources of any market power, the way they collect and use personal data, and whether competition in digital advertising is producing good outcomes for consumers.

"It is our job to ensure that companies innovate and compete. And every bit as much, it’s our job to ensure that consumers are protected from detriment," said CMA Chairman Andrew Tyrie.

Most of the UK population uses the internet, with 97% of internet users accessing search engines to look for things online, and around 70% of UK adults having a social media account. While people enjoy many of these sites for free, revenue from digital advertising provides one of the main ways in which online firms can provide their services without charge.

The market study will examine concerns about how online platforms are using people’s personal data, including whether making this data available to advertisers in return for payment is producing good outcomes for consumers. The CMA will examine whether people have the skills, knowledge and control over how information about them is collected and used, so they can decide whether or not to share it in the first place.

Linked to this, the CMA will consider concerns about the market power of certain sites and examine whether the control they have over people’s data is making it harder for rivals to compete for business, to the detriment of consumers.

The CMA said if it finds evidence that there are problems, it could make detailed recommendations to government.