Nigeria says it cannot meet President Muhammadu Buhari's December deadline to crush Boko Haram's Islamic uprising in the northeast.

Air Commodore Yusuf Anas of the Center for Crisis Communication said on Thursday the deadline was "not tenable."

He warns Nigerians to not view December as a "sacrosanct date when all suicide bombings will end."

Forces from Nigeria and neighboring Chad earlier this year drove the extremists out of areas they had proclaimed an Islamic caliphate. Recently, the Nigerian Air Force and ground troops have reported destroying numerous Boko Haram camps and freeing more than 1,000 kidnap victims.

In June, Buhari ordered the military to crush the insurgency by December, but the extremists have pushed back with village raids and urban suicide bombings that have killed more than 1,500 people.