BRUSSELS, March 2 (Reuters) - Elon Musk's X social media platform, TikTok owner ByteDance and Booking.com may meet EU criteria subjecting them to tough tech rules as so-called gatekeepers, the European Commission said late Friday, after notifications by the companies.

The Digital Markets Act (DMA) designates companies with more than 45 million monthly active users and 75 billion euros ($81 billion) in market capitalisation as gatekeepers providing a core platform service for business users.

Such companies are required to make their messaging apps interoperate with rivals and let users decide which apps to pre-install on their devices, among other obligations, starting from March 7.

They are not allowed to favour their own services over rivals' or prevent users from removing pre-installed software or apps.

"The Commission now has 45 working days to decide whether to designate the companies as gatekeepers. The Commission will also assess any argument put forward by the submitting companies to rebut the presumption that they should be designated as gatekeepers," the EU competition enforcer said in a statement.

ByteDance was labelled a gatekeeper in July last year but TikTok has challenged that at Europe's second-highest court. It is not clear what other ByteDance services could be considered a core platform service under the DMA.

Booking.com last year said it expected to fall into the gatekeeper group this year due to the addition of more users.

Alphabet, Amazon, Apple, Meta and Microsoft were designated gatekeepers last year.

($1 = 0.9228 euros)