Google is facing another probe from the UK’s Competition and Markets Authority (CMA) over whether the company illegally favors its own services.

Google has been under increasing pressure in multiple jurisdictions, with probes and lawsuits over how it conducts business. The CMA was already investigating Google over its ad deal with Facebook, but BBC News is reporting the watchdog is now investigating whether Google illegally used its dominance in the ad business to push its own services.

The investigation is focused on the “ad-tech stack,” of which Google dominates all aspects. In fact, Google’s control of the entire ad stack has been a growing concern in the US as well. Senators recently introduced a bill that would prohibit a company of Google’s size from owning more than one part of the ad ecosystem.

In the meantime, BBC News quoted a Google spokesperson saying the company welcomes the opportunity to work with the CMA:

“We will continue to work with the CMA to answer their questions and share the details on how our systems work.

“Advertising tools from Google and many competitors help websites and apps fund their content – and help businesses of all sizes effectively reach their customers.

“Google’s tools alone have supported an estimated £55bn in economic activity for over 700,000 businesses in the UK – and when publishers choose to use our advertising services, they keep the majority of revenue.”