"The (army) unit rescued 338 persons that were held captive by the terrorists," the army said of an operation on Tuesday, adding that 192 of the survivors were children and 138 women.

The raid targeted "suspected Boko Haram terrorist camps at Bulajilin and Manawashe villages" on the edge of the Sambisa forest, the army said in a statement, adding that troops killed 30 suspected jihadists and seized a cache of arms and ammunition.

The Nigerian military has in recent months claimed a string of successes against Boko Haram in its quest to end the hardline Islamist group's six-year insurgency.

The air force said in a statement on Tuesday it had launched strikes on the group's vehicle and fuel depots "in a renewed drive to further degrade" its assets.

Air force chief Sadique Abubakar was quoted as saying the strikes were helping "pave the way for the final onslaught" by Nigerian ground forces.

President Muhammadu Buhari, who came to power in May on a pledge to crush Boko Haram, has given his military commanders until the end of December to defeat the group, whose insurgency has killed at least 17,000 people and forced more than 2.5 million to flee their homes since 2009.