The US government is asking its allies to stop their domestic semiconductor companies from servicing chipmaking tools for Chinese customers.

The request comes amid the government’s ongoing investigation into an alleged chip sanctions breach by Semiconductor Manufacturing International Corp (SMIC), China's biggest semiconductor company.

Speaking to reporters at a conference, Alan Estevez, who oversees export policy at the Department for Commerce, said: “We are working with our allies to determine what is important to service and what is not important to service.”

In comments published by Reuters, he added: “We're pushing for not servicing of those key components and these are discussions we are having with our allies."

At a congressional hearing earlier this month, Estevez said the department was concerned that SMIC might have been able to produce its 7nm, 5G-enabled Kirin 9000S chip for the Huawei Mate Pro 60 using American tools.

Although not a US-based company, it has previously been reported that SMIC used equipment from Dutch lithography company ASML to manufacture the chips.

The Netherlands has previously given in to pressure from the US, first banning ASML from selling its most advanced equipment to China and then revoking an export license to stop the shipment of two older lithography machines to Chinese customers.

ASML is the sole supplier in the world of extreme ultraviolet lithography (EUV) photolithography machines that are needed to make the most advanced 3nm and 5nm chips. Chinese companies bought 46 percent of ASML's lithography systems sold in the third quarter of 2023, generating around $3.7 billion in revenue between July and November of that year.

In 2022, it was reported that China was trying to build its own ASML competitor, Xtal. The business was founded by an ex-ASML engineer, who was accused of stealing intellectual property from the company.