Gunmen in Nigeria have stormed a Dutch oil barge off the coast, killing two Nigerian navy sailors and kidnapping four foreigners, a naval officer says.
The navy has joined the search for the gunmen off the Niger Delta.
Two navy sailors, among a group providing security, were wounded in the raid.
The foreigners are from Indonesia, Thailand, Malaysia and Iran.
Attacks in the Niger Delta have declined since a 2009 amnesty for militants ended years of conflict.
The ship that was attacked belongs to Sea Trucks Group, based in Rotterdam.