The news follows months of allegations from politicians and soldiers who have told The Associated Press that some senior officers were helping the Islamic extremists and that some rank-and-file soldiers even fight alongside the insurgents and then return to army camps.
They have said that information provided by army officers has helped insurgents in ambushing military convoys and in attacks on army barracks and outposts in their northeastern stronghold.
Leadership newspaper quoted one officer saying that four other officers, in addition to the 15, were found guilty of "being disloyal and for working for the members of the sect."
Boko Haram has attracted international condemnation and UN sanctions since its April 15 abduction of more than 300 schoolgirls, of whom 272 remain captive.
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Leadership newspaper quoted military officers saying the 15 are among many more being tried at divisional level. The verdicts are being referred to defence headquarters in Abuja, the capital, where the fate of the officers will be decided, the newspaper said.
President Goodluck Jonathan said last year that he believed that some members of the military and even of his own government, including some Cabinet ministers, sympathised with Boko Haram or belonged to the group.
The military campaign is backed by a state of emergency in the northeast but it has failed to curb attacks, which actually have increased this year. Jonathan in January fired his entire military command and weeks later replaced the defence minister.
His government and military have been harshly criticised for lack of action that has led to the schoolgirls' prolonged captivity. Defence chief Air Marshal Alex Badeh said last week the military knows where they are being held but fears to use force as it could get the girls killed.