Capt. Obiora Medani said the ship was attacked off Bayelsa state where it was serving as a container for crude oil. The sailor was a guard on the vessel, he said, but did not give the workers" nationalities.

Separately, gunmen seized the mother of the newly elected governor of neighboring Rivers state, police said. The kidnappers made no immediate demands.

"We have some clues and we are working on it," Police Commissioner Felix Ogbaudu said.

Kidnapping foreign workers for cash is common in the lawless southern region. Some abductors make political demands; others demand large ransoms. But they usually release the hostages unharmed.

The groups enjoy protection from local politicians, who are suspected of using them as hired labor to help rig elections scheduled for next month.

Nigeria is one of Africa"s richest countires with oil reserves that generate tens of billions of dollars every year, but the majority of Nigerians remain mired in poverty. Throughout the delta region, poor villagers without access to clean water or electricity live side by side with multimillion-dollar oil installations.

The West African country is plagued by rampant corruption and violent crime.

PIN/WASHINGTONPOST.COM