There have been deadly clashes between security forces and gunmen in north-western Nigeria.
An official statement from the military said troops were ambushed as they advanced on a notorious camp for criminal gangs deep inside a forest near Jibia in Katsina state.
It said 17 bandits had been killed and three soldiers died in Saturday's violence.
But there are reports that the army lost 16 troops - including several senior officers - and 28 others were wounded.
Criminal gangs on bikes frequently attack communities in north-western Nigeria, killing or kidnapping people for ransom as well as stealing livestock.
More than 8,000 people have lost their lives there over the last decade. Military operations and the offer of an amnesty have failed to stop the violence.