"We believe it`s been hijacked and we believe there are about 25 crew on board," Cyrus Mody, a London-based manager with the world`s piracy watchdog told AFP on the phone.
The attack occured on October 30, he said.
Neither the nationalities of the crew nor details of the vessels could be immediately established. A Nigerian navy official was unable to confirm the incident.
It is the latest in a surge of attacks off the coast of West Africa in recent months.
Twenty Eastern European crew hijacked off Nigeria last month were freed along with the vessel around a week later.
The coast of Nigeria, Africa`s largest oil producer, has long been a dangerous place to sail, and the risk has extended in recent months to the coast of the small neighbouring nation of Benin.
Benin`s coast has seen at least 20 piracy incidents this year compared to none in 2010.
Nigeria and Benin launched joint sea patrols last month in a bid to tackle the piracy surge.
The maritime bureau has warned that the spate of ship attacks off West Africa indicates the region could emerge as a new piracy "hotspot". (*)
Editor: Kunto Wibisono
Copyright © ANTARA 2011
