Massoel Shipping, operator of MV Glarus, said the vessel, with 19 crew members aboard and carrying wheat, was traveling between the southwestern commercial capital, Lagos, and the southern Niger Delta oil hub of Port Harcourt when it was boarded by pirates.

It said the attack happened around 45 nautical miles south west of Bonny Island.

"The company is working with the authorities and specialists to secure the speedy and safe release of those being held," Massoel Shipping said in its statement. The statement did not give the nationalities of the crew members.

Switzerland's foreign ministry said it had learned from the company that none of the crew members was from Switzerland itself.

Nigeria's navy and maritime police said they were unaware of the kidnapping and would investigate.

Kidnapping for ransom is a common problem in parts of Nigeria. A number of foreigners have been kidnapped in the last few years in the southern Niger Delta region, source of most of the crude oil that is the mainstay of West Africa's biggest economy. (VOA)

•An aerial view of the oil hub city of Port Harcourt in Nigeria's Delta region. Massoel Shipping's MV Glarus was bound for Port Harcourt on Sept. 22, 2018, when it was boarded by pirates.