A small tanker seized last year by Cambodian authorities over North Korea sanctions-busting allegations is now in the custody of the US.

In a legal filing in the US federal court for the Southern District of New York, attorneys for the US said the 3,900-dwt Courageous (built 1987) had been turned over thanks to an agreement with Cambodian law enforcement.

The filing, made on 23 April, seeks to enforce an arrest warrant issued by a US district judge in April 2020.

"This [action] arises from a national security and counter-intelligence investigation of a scheme to access unlawfully the United States financial system to support illicit shipments to and from [North Korea]," the filing read.

The US said an unnamed Singaporean national acquired the ship for $580,000 in 2019 and used the Courageous to ship gasoline to North Korea twice in the second half of the year — once in a ship-to-ship transfer and once calling on Nampo.

The shipments allegedly violated US and United Nations sanctions.

The Courageous' owner, listed in databases as China-based New Eastern Shipping, was alleged to have used a series of front companies in order to make payments for both the ship and crew in US dollars and through US banks.

The US filing also detailed a four-month period in which the Courageous' AIS went dark, beginning in July 2019, relying on emails to outline alleged attempts to deceive Cameroon into allowing it to stay on its registry.

The ship was dropped by St Kitts and Nevis that August, and went without a flag until November, when it attempted to reflag in the African country.

The filing cites and interprets emails discussing what Cameroonian authorities wanted, including a list of the last 10 ports the Courageous called on, and ownership's apparent attempts to cover them up.

Equasis shows the ship was no longer registered in Cameroon beginning last March.

The Courageous was first detained in Cambodia in March 2020 amid a broader crackdown on North Korean business activity in the country.

Its last AIS broadcast was in September 2020 and shows the ship still in Cambodia.

Should the US forfeiture action succeed, it would be the second ship arrested over the busting of international sanctions after the 27,881-dwt Wise Honest (built 1989) was seized in May 2019.

That ship was towed to the US, auctioned and sold for scrap.