Regulator the Competition and Market Authority (CMA) opened a full investigation in November into the dominance of Apple and Alphabet Inc's Google (GOOGL.O) in mobile browsers, and the possibility of the iPhone maker restricting the cloud gaming market through its app store.

Apple argued that the CMA had "no power" to launch such a probe because it did so too late.

Its lawyer Timothy Otty earlier this month said that the market investigation should have been opened last June at the same time the CMA published a report on mobile ecosystems, which found the two tech giants had an "effective duopoly."

The CAT endorsed Apple's argument, saying that in declining to take action at that time only in the expectation of receiving further powers it might well be said that the CMA "erred in law".

The CMA said it was disappointed with the ruling.

"Today's judgment has found there are material constraints on the CMA's general ability to refer markets for in-depth investigations," it said in a statement.

"This risks substantially undermining the CMA's ability to efficiently and effectively investigate and intervene in markets where competition is not working well.

"Given the importance of today's judgment," it added, "we will be considering our options including seeking permission to appeal."

Apple in a statement issued after the ruling said it believed in "vibrant and competitive markets where innovation can flourish."

"We are pleased with the Competition Appeal Tribunal's decision and will continue working to deliver support for developers and a safe and secure experience for users," the company said.