CBP ordered the immediate detention at all US ports of shipments of Linglong-produced tires from its Zrenjanin factory in northern Serbia, following an "investigation and review of information" indicating forced labor at the facility.

CBP said its assessment drew on "worker statements, documents, photographs, NGO reports, media coverage, and academic research."

Linglong Tire launched mass production at its Serbian plant in September 2024 - the company's first in Europe and a flagship Beijing-backed investment in the Balkans.

But the factory made headlines in 2021 during its construction, when hundreds of Vietnamese workers went on strike amid reports of alleged deception used to lure employees.

Also in February 2024, Serbian civil society groups reported an additional 14 Indian workers allegedly held in forced labour conditions.

Serbian leaders have batted away accusations of malfeasance at Linglong, and company rejected responsibility, saying the workers had been hired by one of its subcontractors.

The European Parliament later called for an inquiry into allegations that Vietnamese workers were trafficked into Serbia and subjected to forced labor.

The US State Department noted in its 2025 Trafficking in Persons Report that the Serbian government "made little progress on an open investigation into allegations of forced labor at this factory."

In the import-halt order, the CBP said evidence showed practices including retention of identity documents, intimidation, isolation, excessive overtime, wage withholding, debt bondage, abusive conditions, deception, and abuse of vulnerability.

"The message is clear-the United States will not tolerate forced labor in supply chains," CBP Commissioner Rodney S. Scott said in a written statement on CBP website.

CBP said importers now may seek to re-export or destroy detained shipments, or prove the goods were not made with forced labor.

Calling it Serbia's largest-ever greenfield investment, President Aleksandar Vucic said at the Linglong 2024 opening ceremony that the "billion dollar plant" employs more than 1,200 workers, is expected to hire 600 more, and aims to generate exports worth 500 million euros in 2025.

Serbia, an EU candidate country, has repeatedly faced criticism over oversight of Chinese-owned firms.

Beijing and Belgrade have had a free-trade agreement since July last year.