Google and Apple Inc face a sweeping probe into the “duopoly” power of their mobile ecosystems, in the UK antitrust watchdog’s latest attack on Silicon Valley.

The increasingly tech-focused Competition and Markets Authority opened a 12-month market study into broad aspects of the iOS and Android systems, saying it feared the companies’ dominance is stifling competition. The investigation adds to the regulator’s separate investigations into both tech giants.

“Our ongoing work into big tech has already uncovered some worrying trends and we know consumers and businesses could be harmed if they go unchecked,” CMA chief executive officer Andrea Coscelli said in a statement.

The CMA uses market studies to gather information before upgrading investigations. The mobile review comes as the UK watchdog seeks to move to the forefront of tech regulation after emerging from the shadow of European Union regulators at the end of the Brexit transition.

The authority is preparing to set up a tech-focused unit and has warned that the largest companies will face extra scrutiny of everything from mergers to monopoly behaviour.

“Android provides people with more choice than any other mobile platform in deciding which apps they use, and enables thousands of developers and manufacturers to build successful businesses,” Google said in an emailed statement. “We welcome the CMA’s efforts to understand the details and differences between platforms before designing new rules.”

Apple declined to immediately comment.

The CMA said it will consider whether Apple and Google use their position as the owners of the main app stores to exploit consumers and developers as well as their supply of mobile browsers.

Big Tech is the focus of a vast array of European probes looking at how the firms increasingly govern the terms of what people do online, often gaining insights into user behaviour that smaller rivals can’t match.

The market study will inform the CMA’s move to boost oversight over the largest tech companies while it develops a new code of conduct for companies that have “strategic market status”. But the regulator also warned that the study could lead to more stringent interventions, noting that even operational splits of company units were a possible outcome.

The CMA is separately scrutinising Apple’s app payment rules and Google’s planned changes to ad tracking.

 - Bloomberg