Microsoft Corp. and an Amazon Web Services Inc.’s dominance in the cloud services market must face an antitrust investigation under the UK’s new rules for digital markets, the country’s watchdog said after a 21 month long investigation.

The dominant position of Amazon and Microsoft in cloud computing is harming competition, with their impact exacerbated by technical and commercial barriers to switching, an inquiry group from Britain's antitrust regulator said.

Britain’s competition regulator called for a probe into Microsoft and Amazon’s cloud market dominance under the country’s strict new tech rules.