The US has sold a North Korean bulker detained in April — but won't say who bought it or for how much.

The 27,881-dwt Wise Honest (built 1989) was sold 12 September, according to the US Marshals Service, and was towed from the port of Pago Pago in American Samoa Tuesday.

"The US Marshals held a sealed bid auction for the seized vessel" from 31 July to 9 August, a service spokesperson said Wednesday.

"A winning bidder was selected ... The US Marshals do not disclose winning bid amounts or the identity of buyers in our sealed bid auctions."

The ship is still listed as North Korean flagged and owned in shipping databases.

The Wise Honest was seized after allegedly carrying machinery to North Korea and coal from it in contravention of US and UN sanctions. The move was hailed as the first-ever vessel arrest over sanctions busting.

The ship, owned by Korea Songi Shipping Company, was said to have picked up coal in Nampo, North Korea on 14 March, 2018. Roughly three weeks later, it was detained by foreign authorities.

It was towed from Indonesia to the US in May. Legal proceedings against the ship went forward in Manhattan federal court, where it was ordered sold in July.

Proceeds from the sale will go to the family of Otto Warmbier, an American college student arrested by North Korean authorities in 2016 and sentenced to hard labour before purportedly suffering a neurological injury, falling into a coma and dying a year later.

The Warmbiers were awarded $501m in Washington, DC federal court in 2018 over their son's death.

The family of Rev. Dong Shik Kim have also filed a claim on the proceeds.

Kim, a South Korean national with permanent residency in the US, was reportedly working with North Korean defectors in China in 2000 when he was abducted by North Korean secret police. He is presumed dead by his family.

In 2015, the Kims won a $330m judgement.

North Korea did not respond to either lawsuit, leaving the Warmbiers and Kims to seize North Korean funds and property in order to pay out the settlements.