LAGOS (REUTERS) - Nigeria's military said on Saturday it had killed 10 insurgents and arrested 65 as part of an offensive meant to wrest back control of parts of its remote northeast from an Islamist group seen as the main security threat to Africa's top oil producer.

A spokesman for Defence Headquarters also said the military had seized stockpiles of weapons including rocket-propelled grenades, guns and ammunition from areas around Maiduguri, the main city in the northeast.

"The Special Forces have apprehended 65 persons confirmed to be terrorists as they made attempt to infiltrate Maiduguri while fleeing from various camps now under attack," Brigadier-General Chris Olukolade said in a statement.

He added that in the Gamburu ward of Maiduguri, the biggest city in the northeast and the place where the Boko Haram uprsing began, "a total of 10 suspected terrorists were confirmed dead while weapons such as Rocket Propelled Grenade launchers, assorted ammunition and rifle magazines were recovered".

The operation against the militant Islamist sect Boko Haram began after President Goodluck Jonathan declared a state of emergency on Tuesday in the states of Borno, Yobe and Adamawa.

Nigerian forces used jets and attack helicopters to bombard militant camps in the northeast on Friday, their biggest offensive since Boko Haram began an insurgency almost four years ago to try to create a breakaway Islamic state.

Nigerian forces are trying to regain territory controlled by well-armed militants in remote semi-deserts in the area around Lake Chad, along the borders with Cameroon, Chad and Niger.