(Adds details, background)
MAIDUGURI, Nigeria, Feb 1 (Reuters) - Nigerian security forces used helicopter gunships to destroy a training camp belonging to the Islamist sect Boko Haram in a northeastern forest on Friday, killing 17 of them in a battle, they said.
Lieutenant Colonel Sagir Musa, spokesman for joint military and police forces in northeastern Borno state, said a soldier had also been killed in the firefight, which cast fresh doubt on a ceasefire declared by one Boko Haram commander this week.
Purported Boko Haram commander Sheik Abu Mohammed Ibn Abdulazeez declared a unilateral ceasefire on Monday, urging members to halt attacks that have killed hundreds since the group launched an insurgency against the government in 2009.
But violence by suspected sect members went on unabated, raising doubts about his authority. Gunmen killed at least five police in two attacks in northern Nigeria on Thursday.
"The camp was properly ... fortified and had training facilities, an armoury, accommodation, a drug store, kitchen, vehicle holding area, latrine and water points," Musa said.
"The camp was used to conduct training and carry out recent attacks, killings and bombings," he said.
There was no immediate reaction from Boko Haram, whose militants have destabilised Africa's top energy producer and raised fears it could become a base for the operations of al Qaeda-linked Islamist groups in the Sahara. (Reporting by Ibrahim Mshelizza; Writing by Tim Cocks; Editing by Louise Ireland)