Five Indian sailors onboard a German oil tanker were kidnapped by heavily armed pirates who attacked the ship in waters off Nigeria's southern coast which have become a hotbed of pirate activity.

The ship's operators, Medallion Marine said today that the ship SP Brussels was attacked roughly 65 kilometres off the oil-rich Niger Delta by pirates who stormed the vessel and looted it before taking five Indians hostage.

"The pirates ransacked the vessel for personal belongings and took five crew members with them on their departure," the operators said in an initial statement and later clarified that the five crew members were Indians.

The Nigerian Navy and the police were not immediately available for comments but Medallion Marine said they are working hand-in-hand with authorities here to get the abducted men released.

The vessel later sailed to a port in Lagos after the pirates left it with the five crew members.

Piracy and oil theft is a regular phenomenon in Nigeria especially in the delta region where oil is produced.

Similar attacks have also been witnessed off the southern commercial city of Lagos.

On September 4, pirates hijacked a ship MT Abu Dhabi Star owned by a Singaporean firm off the shores of Nigeria with its 23 Indian sailors on board. They were later released.

In late August, an oil vessel was seized by pirates off the Coast of Togolese capital of Lome and released few days later near Nigeria with its 23 Russian crew members.

3,000 tonnes of fuel was stolen from the ship, MT Energy Centurion, owned by a Greece-based firm, Golden Energy M.

Meanwhile, Directorate General of Shipping sources told PTI in Mumbai that those held hostage included captain of the freighter, its chief engineer and first officer.

"The authorities concerned have been apprised of the incident and efforts are on to secure safe release of the Indians," they said.