The Daily Times said the two men, named as Romanian master Radu and chief engineer Sergei, were lured from the 9,400–dwt Equinox (built 1993) at a tank farm in Sapele, Delta state, on 19 December.
They were held at a hotel in Warri for more than two weeks by men hoping to extract a ransom, until navy forces eventually freed them.
Two foreigners have been arrested.
Navy commodore Musa Gemu told reporters the case was an indication that hostage taking was not synonymous with Nigerians.
He added: "They kidnapped and held Radu and Sergei captive first at Sapele till late hour and relocated them to a hotel in Warri till December 27th 2014 when NNS Delta patrol team went to rescue them from the hotel, where they were held for almost two weeks.”
The vessel is operated by Maritec of Belgium.
