The charterer of the detained Gourdomichalis brothers ship is moving to seize the more than 51 metric tonnes wheat on board, accusing its owners of breach of contract.

Greek shipbroker Medmar filed suit last week in Oregon federal court, alleging subcharterers of the 52,500-dwt Vigorous' (built 2005) owe them $3.4m for breach of contract and want the cargo held until they pay up. The lawsuit targets Anglo Eastern Navigation and commodities trader Midstar.

According to the complaint, Medmar was owed $2.4m on 13 December, five days after the Vigorous was laden with wheat and set for delivery in Yemen.

The remainder of the alleged debt is estimated interest and legal fees.

The Vigorous, owned by companies associated with George and Stathis Gourdomichalis, was attached 5 December, with Denmark's Pacific Gulf Shipping seeking to collect a $22.6m arbitration award in the 2015 abandonment of the now-scrapped 73,500-dwt Adamastos (built 1995).

Since, the ship has become the subject of an increasingly complicated, worldwide legal tug-of-war.

The registration company owning the Vigorous has argued it cannot be seized because it is not a legal alter ego of the Gourdomichalis-connected companies named in the suit, including Blue Wall Shipping and Trading or Phoenix Shipping and Trading. There is a hearing on a motion to vacate the attachment Wednesday.

Meanwhile, Pacific Gulf brought the Vigorous' insurer, the American Club, into the picture, alleging they are fighting to withhold documents in discovery to defend George Gourdomichalis, the protection and indemnity club's board chairman — an accusation it denies.

Midstar and Al-Saeed Trading Company, the owners of the wheat, have argued in court papers the ship needs to be freed or its cargo loaded into another ship before it goes bad in a race against the clock as the wheat is destined for aid programs in war-torn Yemen.

The motion for attachment of the wheat has yet to be granted.

Christopher Hart, attorney for Midstar, did not immediately return requests for comment.