Nigeria's military destroyed 10 Boko Haram camps in the country's remote northeast on Sunday as it pressed on with an offensive against militant Islamist fighters now confined to a final hideout there, the army said.

A military statement said troops had killed many Boko Haram militants in the Sambisa forest and captured several armored vehicles and anti-aircraft guns. One soldier was killed by a landmine explosion.

Thousands of people have been killed and several million displaced in a six-year Boko Haram insurgency that at its height saw the group control an area the size of Belgium.

But the neighboring states of Chad, Niger and Cameroon launched a combined series of offensives with Nigeria this year that have recaptured nearly all the occupied territory, pushing the remaining militants into the Sambisa forest.

Boko Haram, whose name roughly translates as 'Western education is sinful' in the Hausa language, has hit back with a series of raids over the last week, including two assaults on the regional capital Maiduguri.

"The Nigerian Air force is maintaining an active air surveillance to track the movement of terrorists for appropriate action as the operation continues," army spokesman Chris Olukolade said in the statement.

There has been no comment from Boko Haram, which occasionally puts out statements and videos via the Internet.