LONDON (AP) — Apple and Google aren’t giving consumers a genuine choice of mobile web browsers, a British watchdog said Friday in a report that recommends they face an investigation under new U.K. digital rules taking effect next year.

The Competition and Markets Authority took aim at Apple, saying the iPhone maker’s tactics hold back innovation by stopping rivals from giving users new features like faster webpage loading. Apple does this by restricting progressive web apps, which don’t need to be downloaded from an app store and aren’t subject to app store commissions, the report said.

“This technology is not able to fully take off on iOS devices,” the watchdog said in a provisional report on its investigation into mobile browsers that it opened after an initial study concluded that Apple and Google effectively have a chokehold on “mobile ecosystems.”

The CMA’s report also found that Apple and Google manipulate the choices given to mobile phone users to make their own browsers “the clearest or easiest option.”

And it said that the a revenue-sharing deal between the two U.S. Big Tech companies “significantly reduces their financial incentives” to compete in mobile browsers on Apple’s iOS operating system for iPhones.

Apple said it disagreed with the findings and said it was concerned that the recommendations would undermine user privacy and security.

“We will continue to engage constructively with the CMA as their work on this matter progresses,” Apple said in a statement.

Google did not respond immediately to a request for comment.

It’s the latest move by regulators on both sides of the Atlantic to crack down on the dominance of Big Tech companies. U.S. federal prosecutors this week unveiled their proposals to force Google to sell off its Chrome browser as they target its monopoly in online search.

The CMA’s final report is due by March. The watchdog indicated it would recommend using the U.K.’s new digital competition rulebook set to take effect next year, which includes new powers to rein in tech companies, to prioritize further investigation into Apple’s and Google’s “activities in mobile ecosystems.”