Car manufacturers Toyota, Volkswagen, Tesla, General Motors and BYD may be using aluminium made by Uyghur forced labour in their supply chains and could do more to minimise that risk, Human Rights Watch says.

An investigation conducted by HRW has alleged that while most automotive companies have strict human rights standards to audit their global supply chains, they may not be applying the same rigorous sourcing rules for their operations inside China.

This includes joint venture companies inside China that make models for foreign brands for just the local market and also those that manufacture cars for export and parts that are sent to automobile plants around the world.

While HRW holds broad concerns that aluminium produced by forced labour in Xinjiang could be spreading to car manufacturing operations around the globe, its report identified five companies – Toyota, Volkswagen, General Motors, Tesla and BYD – due to particular concerns it has over their links to specific factories and companies inside China.

HRW’s concerns centre on the link between aluminium smelters in China’s Xinjiang province and what it describes as Chinese government-backed labour transfer programs that allegedly “coerce Uyghurs and other Turkic Muslims into jobs in Xinjiang and other regions”.

The group has alleged that since 2017 the Chinese government has committed crimes against humanity in Xinjiang, including “arbitrary detention, enforced disappearances, and cultural and religious persecution, and has subjected Uyghurs and other Turkic Muslim communities to forced labour inside and outside Xinjiang”.

HRW said there is “credible evidence” that aluminium producers in Xinjiang have received workers from labour transfer programs, as has the local coal industry that energy-intensive aluminium smelters rely on.

The organisation said its research relied on Chinese state media, company reports and government statements available online, because of “the high level of repression and surveillance in Xinjiang, including threats to workers and auditors” that make it impossible for both human rights groups and car companies to conduct credible investigations into allegations of forced labour.

More than 15% of aluminium produced in China, or 9% of global supply, now comes from Xinjiang. While most of Xinjiang’s aluminium leaves the region in the form of aluminium ingots and changes hands through various minerals traders, these ingots are then melted down and mixed with other materials in other provinces of China, the report said.

Once the ingots are melted with other aluminium, “it is impossible to determine whether or how much of it came from Xinjiang, potentially enabling tainted aluminium to enter domestic and global supply chains undetected”, HRW said.

“While the Chinese government has welcomed car companies’ investments on its own terms, it has so far shown hostility to the human rights and responsible sourcing policies many carmakers profess to apply across their businesses,” the report said.

HRW has highlighted its concerns as China’s appetite for aluminium increases, with its research claiming that domestic and foreign manufacturers in China produced and exported more cars than any other country in 2023.

Meanwhile, carmakers accounted for about 18% of all aluminium consumed globally in 2021, according to the International Aluminium Institute. The metal is also critical to car parts, including alloy wheels, as well as components such as batteries for electric vehicles, with its lighter weight allowing greater travel distances.

While HRW’s report acknowledges the Chinese government uses the claim of political sensitivity regarding Xinjiang as a “carte blanche” to quash discussion on human rights abuses, it argues car companies could still do more to minimise the risks of relying on aluminium produced by forced labour.

Car companies could move to directly source their aluminium from smelters outside Xinjiang, HRW said. Manufacturers could also demand better source mapping and information from their aluminium suppliers, even if under the guise of auditing their commitments to reduce greenhouse gas emissions.

Jim Wormington, an HRW senior researcher, said that because China was increasingly a manufacturing base for cars for export, “there’s absolutely the risk you could be driving a vehicle on the roads in places like the EU and Australia that contains aluminium linked to forced labour in Xinjiang”.

“What we’re asking car companies to do is really having a strategy … As the car industry is the world’s biggest user of aluminium, it can send a really powerful message,” Wormington told the Guardian.

HRW also wants to see strict laws – in line with the US’s Uyghur Forced Labor Prevention Act – to block the importation of anything potentially linked to state-enforced forced labour. This would put the onus on the importer to demonstrate their goods aren’t linked to forced labour.

“There should be an assumption that anything manufactured in Xinjiang is linked to forced labour … Governments should send a clear message that access to their consumers is contingent on demonstrating products aren’t linked to forced labour,” Wormington said.

Toyota did not answer questions from HRW researchers. In a statement sent to the Guardian, Toyota said the HRW report “will be closely reviewed”. “We expect our suppliers to follow our lead to respect and not infringe upon human rights,” it said.

Chinese manufacturer BYD did not answer questions from HRW researchers or respond to the Guardian’s inquiries.

Volkswagen told HRW that because it holds 50% of equity with its joint venture SAIC, it is not legally responsible for human rights impacts in their joint venture’s supply chain under German law because it doesn’t have “decisive influence”. However, the company acknowledged that it had “blind spots” over its global supply chain for aluminium.

A Volkswagen spokesperson told the Guardian it is “actively reviewing and using our existing procedures and looking for new solutions to prevent forced labour in our supply chain” and that it “takes its responsibility as a company in the area of human rights very seriously worldwide – including in China”.

Tesla told HRW it had conducted mapping audits of its aluminium supply chain which found no evidence of forced labour. Tesla did not respond to the Guardian.

General Motors told HRW it “is committed to conducting due diligence and working collaboratively with industry partners, stakeholders, and organizations to address any potential risks related to forced labor in our supply chain”. GM did not respond to the Guardian.