The Nigerian military says it has rescued 13 hostages seized by militants in the oil-producing Niger Delta region.

Military officials say nine Filipinos and four Nigerians were freed in operations against the region's most prominent militant group, the Movement for the Emancipation of the Niger Delta or MEND.

Both the rebels and the military say two other hostages were killed in the fighting.

The hostages had been held since Wednesday, when militants hijacked two ships in the Niger Delta.

The military responded by attacking a major militant camp in Delta state Friday.  Military officials say the camp was destroyed, while a statement from MEND Sunday said fighters had evacuated with weapons and ammunition intact.

The Nigerian military is trying to subdue militants whose attacks have cut Nigeria's oil production by more than a third since 2005.

Sunday's statement from MEND said the group has blown up two major oil and gas pipelines.  There was no immediate confirmation of thse attacks.

The group also said it has relocated a British hostage, Matthew Maguire, to a camp in Delta state.  The move suggested MEND is using Maguire as a human shield to discourage further fighting in that area.

MEND says it is fighting to secure more of the Delta region's oil wealth for local residents.  The government has dismissed the group as criminals and bandits.

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