By Foo Yun Chee

BRUSSELS EU antitrust regulators are asking Microsoft's users and rivals whether Bing should comply with new tough tech rules and also whether that should be the case for Apple's iMessage, people familiar with the matter said on Monday.

The European Commission in September opened investigations to assess whether Microsoft's Bing, Edge and Microsoft Advertising as well as Apple's iMessage should be subject to the Digital Markets Act (DMA).

The probes came after the companies contested the EU competition regulator labelling these services as core platform services under the DMA.

The DMA requires Microsoft, Apple, Alphabet's Google, Amazon, Meta Platforms and ByteDance to allow for third-party apps or app stores on their platforms and to make it easier for users to switch from default apps to rivals, among other obligations.

The Commission sent out questionnaires earlier this month, asking rivals and users to rate the importance of Microsoft's three services and Apple's iMessage versus competing services.

The people familiar with the matter said the EU watchdog asked if there was anything specific to the services that business users rely on and how they fit into the companies' ecosystems.

It also asked for the number of users using the services.

Respondents were given less than a week to provide feedback. The Commission wants to complete its investigation within five months.

(Reporting by Foo Yun Chee, editing by Deborah Kyvrikosaios and Angus MacSwan)