Apple AAPL.O and Google GOOGL.O have agreed to make their mobile app stores fairer and more transparent for thousands of developers, Britain's antitrust regulator said on Tuesday, hailing it as important first steps in its tougher regime.

The Competition and Markets Authority (CMA) designated the two tech giants as having "strategic market status" in smartphones in October, giving it the power to demand specific changes to boost competition.

Nearly all smartphones in Britain run either Apple iOS or Google's Android operating systems, and their app stores and browsers have exclusive or dominant positions on their platforms.

Under the new commitments, the companies will review apps in a fair, objective and transparent way, the CMA said.

Developers will also be able to request access to more of Apple's features in iOS to create competing products, for example related to digital wallets or live translation.

The regulator has previously said this dominance enables the two companies to exert considerable influence over content, services and technological developments.

Apple said it faced "fierce competition in every market where we operate, and we work tirelessly to create the best products, services and user experience".

"The commitments announced today allow Apple to continue advancing important privacy and security innovations for users and great opportunities for developers," it said.

Google said that while it believed its existing developer practices were fair, objective, and transparent, it welcomed the opportunity to resolve the CMA’s concerns collaboratively.

-Reporting by Paul Sandle and Sam Tabahriti; Editing by Kate Holton/Reuters