Six Turkish crew members on a private tanker who were taken captive two weeks ago by pirates off Nigeria have been released, said a lawyer representing the company owning the tanker on Tuesday.

"The personnel have been undergoing a health check and they are all in good [condition]," said Fehmi Ülgener in a statement, also thanking Turkish officials for their support.

Ülgener said that crew members İlkay Olgun, Haluk Buran, Furkan Topçu, Mehmet Babacan, Şükrü Dömbek, and Eray Falay were released on Monday, but when contacted, his office gave no further details.

Turkey's Ambassador in Abuja Hakan Çakıl had told Anadolu Agency that the private Turkish tanker Puli, a merchant vessel designed to transport liquids or gases in bulk, was seized by Nigerian pirate gangs on April 11.