The Call of Duty developer Activision Blizzard has accused the UK of being “closed for business” after the competition regulator blocked its attempted takeover by Microsoft, which would have been the largest acquisition in gaming history.

The Competition and Markets Authority (CMA) prevented the $68.7bn (£55bn) cash purchase because of concerns it would squash the cloud gaming market, sparking furious pushback from both sides of the deal. Microsoft said it would “discourage technology innovation and investment in the UK”, while Activision Blizzard vowed to “reassess our growth plans for the UK”.

The tie-up would have created a gaming behemoth, merging Activision’s plethora of “AAA” titles, which also include World of Warcraft,