Microsoft faces a dispute in the U.K. over how it charges customers who buy cloud software services that rival its own Azure, the latest antitrust challenge to the U.S. tech giant’s approach to licensing.

Microsoft faces legal action in Britain over a claim that thousands of businesses using cloud computing services provided by Amazon, Google and Alibaba could be paying higher licence fees to use Windows Server software.

Microsoft was accused of unfairly overcharging customers of rival cloud companies including Amazon, Google and Alibaba Cloud in a U.K. lawsuit filed Tuesday.

Microsoft is in the crosshairs of a U.K. competition class-action style lawsuit that's seeking £1 billion (around $1.25 billion at current exchange rates)