Illustration picture of U.S. and Chinese flags
Flags of U.S. and China are seen in this illustration picture taken August 2, 2022.

The United States on Friday added China's top memory chipmaker YMTC and 30 other Chinese entities to a list of companies that U.S. officials have been unable to inspect, ratcheting up tensions with Beijing and taking aim at a firm that has long troubled the Biden administration.

The new listings were the first of a slew of new restrictions announced on Friday on exports of technology to China aimed at blocking its military advances.

As Reuters exclusively reported on Thursday, the United States is also set to curb access to chipmaking tools for Chinese firms including Yantze Memory Technologies Co (YMTC), while still allowing South Korean memory chipmakers Samsung Electronics Co Ltd and SK Hynix Inc to obtain the equipment for their operations in China.

U.S. senators from both parties have been calling for YMTC, China's fast-growing chip manufacturer, to be placed on a trade blacklist known as the "entity list." The company, founded in 2016, is seen as a "direct threat" to U.S. chip companies by the Biden administration.

YMTC and the Chinese embassy in Washington did not immediately respond to requests for comment.

YMTC is under investigation by the Commerce Department over whether it violated U.S. export controls by selling chips to blacklisted Chinese telecommunications company Huawei Technologies Co Ltd. Its chips also are being evaluated by Apple Inc for inclusion in some of its iPhones in China, a major concern for U.S. lawmakers and the Biden administration.

Companies are added to the unverified list because the United States could not complete on-site visits to determine whether they can be trusted to receive sensitive technology exports from the United States.

U.S. exporters must conduct additional due diligence before sending goods to entities placed on the "unverified list," like the 31 added on Friday, and may have to apply for more licenses.

The United States removed a unit of Wuxi Biologics from the list on Friday, good news for the maker of ingredients for AstraZeneca's COVID-19 vaccine. Reuters reported last summer that U.S. officials had been able to conduct an inspection at the Wuxi city site, a stepping stone to removal from the list.

A Wuxi Biologics spokeswoman said on Friday the company was pleased the Wuxi site was removed from the list, given the inspection in June. The company looks forward to scheduling an inspection of its Shanghai subsidiary, which also was placed on the unverified list in February, she added.