Federal prosecutors are investigating Huawei Technologies, the world's largest telecommunications equipment maker, for allegedly stealing trade secrets from US businesses and could soon issue an indictment, the Wall Street Journal reported on Wednesday.

Citing people familiar with the matter, the Journal said that one area of investigation is the technology behind a device that T-Mobile US Inc used for testing smartphones. Reuters could not immediately confirm the report.

The action is the latest in a long list taken to fight what some in the Trump administration call China's cheating through intellectual property theft, illegal corporate subsidies and rules hampering US corporations that want to sell their goods in China.

The investigation arose out of civil lawsuits against Huawei, the Journal said, including one in Seattle where Huawei was found liable for misappropriating robotic technology from T-Mobile.

A Huawei spokesman and a spokeswoman for the US attorney in the western district of Washington declined comment.

T-Mobile alleged in a 2014 lawsuit, filed in federal court in Seattle, that Huawei employees stole technology relating to a smartphone-testing robot T-Mobile had in a lab in Bellevue, Washington.

The robot, Tappy, used human-like fingers to simulate tapping on mobile phones.

According to T-Mobile's lawsuit, Huawei employees photographed the robot and attempted to remove one of its parts.

In May 2017, a jury said Huawei should pay T-Mobile $4.8 million in damages.