The tech giant could be compelled to permit competing app stores within the United Kingdom.
Apple may have to allow competitors to operate their own application platforms on iPhones across Britain, after a ruling from the market watchdog.
This would be a significant change to the company's well-known "closed system" where apps can only be installed from its own App Store.
But the UK competition watchdog has designated both Apple and Google as having "strategic market status" - effectively saying they have significant control over mobile platforms.
Regulatory Assessment
The regulator said the two companies "may be limiting innovation and competition".
But the authority emphasized it did not "determine or presume wrongdoing" from the companies.
"Mobile applications generates 1.5% of the British economy and supports around four hundred thousand positions, which is why it's essential these sectors function properly for enterprises," stated a senior official from the competition authority.
Approximately ninety to one hundred percent of British smartphones run on the two tech companies' mobile platforms, creating what the authority calls an "virtual monopoly".
Based on recent analysis, 48.5% of UK mobile owners use an Apple device - which runs Apple's iOS - with the vast majority of the rest using Google's Android.
Apple's Reaction
The regulatory probe examined how prominent Apple and Google's own apps are compared with competitors - as well as their web applications and operating systems.
It is unclear what modifications the authority will look to request, but previously it published guidelines detailing potential measures it could take.
These include requiring it to be more straightforward for people to transition between iOS and Android devices, and for both firms to rank apps "fairly and openly" in their marketplaces.
The Cupertino company specifically may be required to permit alternative app stores on its products, and enable people to install apps straight from developer sites.
This would follow comparable regulations in the EU, which previously imposed measures against the company for anti-competitive behaviour.
The technology firm warned the UK could face delays to getting new features - as has occurred in the European Union - which the company blames on heavy regulation.
For example, some Apple Intelligence features which have been launched in other regions are not accessible in the EU.
"We faces fierce competition in every market where we operate, and we strive continuously to create the best products, solutions and customer interface," the organization said in a statement.
"The UK's adoption of EU-style rules would undermine that, leaving users with reduced data protection and safety, delayed access to new features, and a divided, more complicated experience."
Google's Position
Google device owners can currently use alternative marketplaces - though critics say they are not as user-friendly as Google's own Play Store.
The regulator's plan said Google may have to "change the user experience" of installing applications directly from websites, as well as "eliminate barriers" when using alternative app stores.
"We simply do not see the rationale for today's designation decision," a company policy executive stated.
The executive said "the majority" of Android users use third-party platforms or install applications directly from a developer's website, and asserted there is a much wider selection of apps offered for Android users compared to those on iOS products.
"There are now twenty-four thousand Android phone models from thirteen hundred device makers globally, facing intense competition from iOS in the United Kingdom," the representative continued.
Google's platform is an freely available software, which means creators can use and build on top of it for free.
The company contends this means it promotes competition.
But consumer groups said restrictions on these companies' power in different nations "are already helping enterprises to develop and giving consumers more choice".
"Their dominance is now causing real harm by limiting options for consumers and market rivalry for companies," stated a policy expert.