The wife of the Ukrainian captain of a Maltese-registered ship is calling on Greek authorities to release him and his crew after six weeks of captivity.

The captain is being held in an Athens prison while the 16-man crew are being held on board the ship - the Mekong Spirit - at Souda Bay Naval Base, Crete.

Captain Sergii Nevecheria, 61, was detained on 23 May while the ship was transiting Greek waters after stopping in Izmir, Turkey.

READ: Malta-registered ship found carrying explosives

The Greek authorities allege that the ship was carrying mining explosives and hunting/sport rifle cartridges destined for Port Sudan in violation of UN and EU sanctions.  

Valentina Nevecheria, the captain's wife, said her husband was very proud of how he ran his ships and would never do anything that would harm anyone.

"He has been held in horrible conditions in a prison cell for six weeks without having any chance to prove his innocence," she told the international media.  

The ship's owners insist that all documentation and import permits for their cargo were in hand.

"We have cooperated fully with Greek authorities and provided all relevant cargo manifests to show that the vessel's cargo of mining explosives and hunting rifle cartridges was for civil use and complied fully with all relevant UN and EU regulations and sanctions," they said.