LONDON (Reuters) - Amazon (AMZN.O) has told the UK's antitrust authority its rival Microsoft (MSFT.O) uses business practices that restrict customer choice in the cloud computing market, the second major company to criticise the U.S. tech company's operations.

The comments were made in a letter published on the Competition and Markets Authority's (CMA) website on Tuesday after it launched an investigation into Britain's cloud computing market in October.

Last week, Reuters reported Google (GOOGL.O) had submitted a similar letter to the watchdog, claiming Microsoft’s business practices had left its rivals at an unfair disadvantage.