The EU has started asking rivals about Google’s advertising practices, just two years after closing a decade of investigations into the company’s shopping, advertising and Android businesses that led to €8.2bn of fines.

Regulators in Brussels have sent questionnaires to publishers and advertising companies asking them about Google’s position in the online advertising market, where it acts as the dominant middleman between publishers and advertisers. The questions may or may not lead to a formal inquiry.

Google’s technology stack has unrivalled scale in serving automated ads on websites in the open internet, putting buyers and sellers together, providing data and overseeing auctions for ad inventory.

The move by EU investigators comes after regulators in the US accused Google in December of abusing its monopoly and colluding with Facebook to shut out rival ad exchanges.

The main concerns of the EU relate to whether Google abused its position to structure auctions to its own benefit and tied parts of its ad services in contracts, to the detriment of publishers and advertisers. In the online advertising market, intermediary fees often range between 40 and 60 per cent of the money spent by advertisers.

The questionnaire contains a range of inquiries about Google’s behaviour and how companies feel about a series of rule changes, such as the decision by Google in 2016 to combine the data it gathered from people logging into Google services, such as Google Maps and Gmail, with the data it gathered from online searches.

“Certain practices may create obstacles to entry and expansion of competitors and/or protect Google’s position in potential markets that relate to the collection, access, processing, use and monetisation of data, as well as neighbouring and downstream markets for the provision of online services,” the questionnaire said.

The questionnaire also asked companies to outline the importance of YouTube, which is owned by Google, for their ad campaigns, and their overall ad spend on search campaigns on Google Ads. Regulators also asked companies if Facebook can be regarded as a rival to Google. The deadline for submitting answers is Friday.

The questions are part of an investigation into the way Google collects data that started in 2019.

Google said: “We compete with many others in the industry and give people granular controls over how their information is used to personalise ads and limit the sharing of personal data to safeguard people’s privacy. We have been engaging with the Commission and others on this important discussion for our industry and will continue to do so.”

The company is still contesting its earlier EU fines in court. Politico first reported on the questionnaires.