Chinese authorities have filed a case to investigate U.S. parcel delivery service FedEx for allegedly undermining the rights of Chinese clients, state-run Xinhua news agency reported on Saturday.

According to Xinhua, FedEx failed to deliver express packages to designated addresses in China, "seriously damaging the lawful rights and interests of its clients and violating laws and regulations governing the express industry in China."

The Chinese government's move against FedEX comes after Chinese tech company Huawei said it was re-assessing its relationship with the U.S. parcel delivery service after several packages were diverted.

Huawei accused FedEx of diverting two packages postmarked from Japan and destined for company addresses in China to the United States without providing detailed explanation, according to Reuters news agency. FedEx also allegedly attempted to re-route two other packages sent from Vietnam to Huawei addresses elsewhere in Asia without authorization.

Huawei said all four packages contained documents and no technology.

The Trump administration blacklisted Huawei from purchasing U.S. components after declaring a national emergency over threats to U.S. technology last month. The administration has subsequently eased those restrictions, allowing Huawei to buy U.S. components for 90 days to maintain existing networks.

Washington and Beijing are locked in escalating trade war after the collapse of trade negotiations. The U.S. has more than doubled tariffs on $200 billion of Chinese goods and has threatened to tax all Chinese imports. China has increased tariffs on $60 billion of U.S. goods.