WASHINGTON (AFP) - The US customs agency announced on Friday (May 28) it would block imports of products from China's Dalian Ocean Fishing Co for alleged use of forced labour and abuse of workers on its tuna vessels.

The Customs and Border Protection issued a "withhold release order" on any products from Dalian Ocean shipped to the United States, meaning importers cannot take possession of them.

"Companies that exploit their workers have no place doing business in the United States," said Homeland Security Secretary Alejandro Mayorkas.

"Products made from forced labour not only exploit workers, but hurt American businesses and expose consumers to unethical purchases."

CBP said it had evidence of forced labour, withholding of wages, and abusive working and living conditions aboard Dalian's vessels.

The withhold release order is applied to any seafood from the company, which operates 33 longline tuna vessels.

CBP has in the past issued similar import blocks on specific Chinese fishing boats, but never before on an entire company's fleet.

Dalian Ocean has been accused several times of abuse by human rights and environmental groups.

South Korea-based Advocates for Public Law and the Environmental Justice Foundation said last year that one of Dalian Ocean's vessels, the Long Xing 629, had refused medical care for four crewmen suffering from unspecified ailments.

Three died aboard the ship and their bodies were dumped overboard, while a fourth died after returning home to South Korea.

Indonesian workers aboard the vessel said they worked 18 hours a day, were paid only a fraction of the promised US$300 (S$397 million) a month salary, saw wages withheld, didn't dock in a port for more than a year, and were given salty water to drink.

In addition, the groups say the vessel was involved in illegal, large-scale harvesting of sharks for their fins.