A Chinese company bought at least $7.4 million worth of copper alloy ingots from a plant in a Russian-annexed region of Ukraine that is subject to Western sanctions, according to Russian customs data reviewed by Reuters.

China has not imposed any restrictions on trade with Russia, but the United States has threatened to blacklist companies round the world for violating its sanctions and warned Beijing against supplying Moscow with goods banned by U.S. export rules.

The customs information, drawn from one commercial trade data provider and cross-checked with two others, show some of the first evidence of Chinese trades with Russian-annexed regions of Ukraine since the war began on Feb. 24 2022.

The Chinese firm, Quzhou Nova, bought at least 3,220 tons of copper alloy in ingots worth a total of $7.4 million from the Debaltsevsky Plant of Metallurgical Engineering between Oct. 8, 2022 to Mar. 24, 2023, according to the data.

The plant is located in the Donetsk region of eastern Ukraine, close to the border with Luhansk. Both Donetsk and Luhansk were among four Ukrainian regions that President Vladimir Putin claimed last September as part of Russia.

Quzhou Nova, a trading and manufacturing company based in the city of Quzhou in the eastern province of Zhejiang, told Reuters it does not have any import and export business related to the trade of copper alloy in ingots.

When Reuters showed details of the exports in the customs data to Quzhou Nova, the company said on March 23 that it “finds hard to understand the document, because this document is not stamped and signed”, and suggested contacting customs about the issue.

The database, which collects information on all shipments worldwide, does not display stamps or signatures on its information.

The Chinese customs service did not provide detailed information on imports. It said that “company trade data are not disclosed in our public information”.

China imported copper and copper alloys worth $852 million from Russia between October and February, according to public customs statistics.

A source at the Debaltsevsky plant, who spoke on condition of anonymity, said there was a non-ferrous metallurgy workshop on the territory of the factory. The source declined to comment on the issue of copper alloy shipments to China, saying the information was a “trade secret”.

Contacted for comment, the Russian Federal customs service told Reuters that information on companies is confidential and is not disclosed by the service.

The Debaltsevsky Plant did not respond to Reuters requests for comments by phone and in writing.

Ukraine, its Western allies and an overwhelming majority of countries at the U.N. General Assembly have condemned Russia’s declared annexation of the four regions as illegal.

SANCTIONS U.S. sanctions imposed on Feb. 21, 2022, three days before Russia invaded Ukraine, prohibit U.S imports from or exports to the so-called Donetsk and Luhansk People’s Republics.

Two days later, the European Union announced measures including an import ban on goods from the two regions.

While Chinese companies are free as far as their authorities are concerned to trade with firms in Russian-controlled regions of Ukraine, they do risk being added to Western blacklists.

Asked about the copper shipments data, the U.S. State Department said it was concerned about China’s alignment with the Kremlin.

“We have warned the PRC (People’s Republic of China) that assistance to Russia’s war effort would have serious consequences. We will not hesitate to move against entities, including PRC firms, that help Russia wage war against Ukraine or help Russia circumvent sanctions,” it added in a statement to Reuters, listing some Chinese companies already sanctioned.

The European Comission did not respond to Reuters’ questions as to whether Chinese companies cooperated with the Russian-annexed Ukrainian territories and what risks such activity posed.

China’s Ministry of Commerce did not respond to Reuters’ requests for comment about the shipments of copper alloys from the Debaltsevsky Plant or cooperation with businesses in the Donetsk region.

The data seen by Reuters is based on shipping and customs documents like bill of lading and shipping bills and collected from several customs departments, government bodies and other partners.

Quzhou Nova says it specialises in the export of wrapping paper. According to its website, it manufactures and trades goods for the tobacco industry, including paper, aluminium foil and polypropylene film.

Reuters could not establish what use the copper alloy was intended for.

The Ukrainian plant, located in the city of Debaltseve 70 km (45 miles) from the Russian-controlled Ukrainian city of Donetsk, specializes in making equipment and spare parts for ferrous metallurgy, the mining industry and cement plants, and has steelmaking and metal casting workshops, according to its website.

Reuters was not able to find any data about the financial state of the company. It was added to the Russian state tax register in December 2022 and has yet to report financial data.

According to a Ukrainian register, the legal status of the plant in Debaltseve has been suspended by the Ukrainian authorities. The register does not indicate when or why this happened.

As of early 2023, its only owner was the Ukrainian Donetsk regional state administration.

The Ukrainian government, as well as the Russian-appointed Donetsk People’s Republic administration, did not immediately comment to Reuters about cooperation with Chinese companies and shipments of goods to China.

The copper alloy shipments from the plant were carried out via the port of Novorossiysk in southern Russia, according to the customs data.