Nigerian hospital officials say the death toll from an ambush in northeastern Nigeria has risen to 48 people.

The officials say the bodies of 18 soldiers and 30 others have been brought to Maiduguri from the area near Lake Chad where extremists Boko Haram fighters attacked geological surveyors who were prospecting for oil Tuesday.

The military has put the toll at 10 dead, and the government has suspended oil prospecting in the area.

The attack comes five days after Nigeria's army issued a directive for the arrest of the Boko Haram leader, Abubakar Shekau, within 40 days.

Authorities say a separate attack Thursday near Maiduguri killed several female suicide bombers.