Electric vehicle batteries and other auto parts are the latest products to come under scrutiny in the US as part of Washington’s push to eliminate US links to forced labor in Chinese supply chains, according to a document seen by Reuters and statistics and sources, reports Reuters.

So far, enforcement of a year-old US law banning the import of goods made in Xinjiang, China has focused mainly on solar panels, tomatoes and cotton clothing, according to News.ro.

But now, components that can include lithium-ion batteries, tires and the major automotive raw materials aluminum and steel are increasingly subject to border detention.

Increased inspection of products destined for auto assembly plants by US Customs and Border Protection (CBP) could signal difficult times for automakers who will need strong evidence that their supply chains do not have ties to a region in which the US believes that Chinese authorities have established forced labor camps for Uyghurs and other Muslim minority groups.

Beijing denies any abuse.

The enforcement of the Uyghur Forced Labor Prevention Act (UFLPA) for more than 1 year has already slowed the development of solar projects as the detained panels sit in US warehouses.

Installations of solar equipment for utilities fell 31 percent last year due to limited panel supplies, according to the U.S. Solar Industries Association trade group, which said conditions have improved somewhat this year.

Both solar power and battery-powered electric vehicles are critical industries in the Biden administration’s effort to wean the US off fossil fuels and combat climate change.