The Turkish-flagged Paksoy-I cargo vessel, operated by shipping company Kadioglu Denizcilik, was attacked on Monday night, state news agency Anadolu said.
A Kadioglu Denizcilik employee who wished to remain anonymous told AFP that 10 Turkish sailors were kidnapped among 18 crew members on board the ship.
The employee denied local media reports that two sailors had since been freed.
A company statement cited by Turkish media said the ship was attacked by “pirates” on its way from Cameroon to the Ivory Coast. It was carrying no freight.
Turkey’s ruling party spokesman Omer Celik said a ship with Turkish crew was “seized” off Nigeria, but did not provide further details.
Celik said Turkish authorities were following the issue closely.
Pirates normally seize sailors for ransom. Nigeria reported 14 pirate attacks in the first quarter of 2019 compared to 22 in the same period in 2018.
An International Maritime Bureau (IMB) report in April attributed the drop to the Nigerian navy’s increased efforts to “actively respond to reported incidents by dispatching patrol boats.”