The second major company to condemn the U.S. tech giant’s operations, Amazon, has informed Britain’s antitrust watchdog that its rival, Microsoft, adopts business practises that limit customer choice in the cloud computing industry.

In October, the UK’s Competition and Markets Authority (CMA) opened an inquiry into the nation’s cloud computing sector after media watchdog Ofcom brought attention to Amazon and Microsoft’s hegemony in the space.

Amazon claimed that consumers were finding it more difficult to move to other cloud providers or to use rival services side by side as a result of modifications to Microsoft’s terms of service, in a letter that was posted on the CMA website on Tuesday.

“To use many of Microsoft’s software products with these other cloud services providers, a customer must purchase a separate license even if they already own the software,” Amazon said. “This often makes it financially unviable for a customer to choose a provider other than Microsoft.”

According to Reuters last week, Google wrote a similar letter to the watchdog, arguing that Microsoft’s business policies had unfairly disadvantaged its competitors.

Google presented the CMA with six proposals, among them the requirement that Microsoft enhance interoperability for users utilising both its Azure service and other cloud services, and the prohibition against Microsoft delaying security updates from users who decide to switch.

Microsoft claimed that the British cloud computing market was still competitive in their own submission to the CMA.

“There are many sources of competition in the cloud market in the UK. Google, Oracle, IBM and many other cloud players are also investing billions of pounds in cloud infrastructure globally to satisfy demand and are competing strongly for each customer workload where they operate,” it wrote.

(Adapted from MarketScreener.com)