Li Ning was required to provide evidence within 30 days that its merchandise was not produced with convict labour, forced labour or indentured labour, or it “may be subject to seizure and forfeiture”, the CBP said on its website.

The Countering America’s Adversaries Through Sanctions Act (CAATSA) prohibits the entry of merchandise involving North Korean labour anywhere in the world, unless evidence is provided that such goods are not made with forced labour.

Li Ning did not respond immediately to Reuters’s inquiry for comment on Wednesday.

The CBP said the company’s products had been held at ports since March 14.

Li Ning generated 98.9% of its revenue in China and only 1.1% from abroad, according to its latest earnings report.

Norway’s US$1.3 trillion sovereign wealth fund earlier this month said it had excluded Li Ning due to “unacceptable risk” the company was contributing to human rights abuses in Xinjiang, China.

Chinese apparel companies have come under scrutiny over their use of cotton from the Xinjiang region after reports of human rights abuses against Uighur Muslims there. China denies all such abuses.

In March last year, Li Ning told the Global Times newspaper that Xinjiang was an important raw material producing area in its supply chain.