Gunmen in Nigeria have taken six Filipinos hostage after attacking their vessel near a key oil terminal in the south.

Authorities Saturday said armed men carried out the assault near the Bonny export terminal in the Niger Delta region.

Separately, Nigerian military officials said kidnappers Saturday released a British man they captured in the Delta last month.  They said no ransom was paid and that the man was released unharmed.

Militants have been attacking foreign oil installations in the Niger Delta since 2005, claiming they want local residents to get more of the region's oil wealth.  But armed gangs also have carried out kidnappings for ransom.

This week, Nigeria's military said it arrested 400 suspected militants after a series of recent attacks.  They said the raids were carried out near Port Harcourt, the country's oil industry hub.

The attacks have reduced Nigeria's oil output by more than 20 percent.

Some information for this report was provided by AFP and Reuters.