The United States has asked China to revise new export quality control rules for protective equipment needed in the coronavirus outbreak so they are not an obstacle to timely supplies, a spokesman for the U.S. State Department said.

China tightened restrictions on exports of masks and other personal protective equipment (PPE) a week ago, calling for shipments to be subjected to a mandatory customs inspection.

The move followed highly publicized complaints from some governments and hospitals that they received PPE from China that they considered faulty.

“We appreciate the efforts to ensure quality control. But we do not want this to serve as an obstacle for the timely export of important supplies,” a State Department spokesman said late on Thursday.

“The U.S. Government has raised these concerns with (China). We have requested that China revise its new requirements to allow the expeditious export of vital PPE to the United States,” he said.

The United States is heavily reliant on medical supplies produced in China, a major strategic and trade rival, something that has been highlighted in the pandemic, in which the United States has been the worst-hit country.

On Friday, Republican Senator Kelly Loeffler accused China of holding up shipments of test kits.

The Chinese embassy in Washington said countries worldwide were “hunting for medical supplies, causing a big challenge for China in quality control and regulation of export.” It said to streamline procedures, a “green channel” had been set up for Chinese manufacturers to register their supplies.