The Greek Ministry of Merchant Marine announced on Sunday that three of the five crew members of the Togolese-flagged Stelios K supply ship were abducted on November 16 when the attackers boarded the vessel.
According to the ministry, the company Royal Ship Management, owner of the tanker, is in discussions to release the sailors.
The pirates kidnapped the captain and two crew members of the Stelios K.
The two remaining sailors were able to pilot the boat to Lagos.
This is the 23rd kidnapping in the Gulf of Guinea this year. A total of 118 people were kidnapped, according to the British company Dryad Global, which specializes in maritime security.
The latter issued a "critical risk assessment" for the Gulf of Guinea immediately after the kidnapping of the Greeks, explaining that it was the second such case in three days against a backdrop of "sharp increase in incidents" security in the region.