Ten soldiers have been killed by a government air strike in the embattled city of Marawi in the Philippines.
Eight soldiers were also wounded in the “friendly fire” incident on Wednesday, said defence secretary Delfin Lorenzana, expressing remorse.
Over the last week militants allied to the so-called Islamic State have engaged in street battles with the army leaving more than 100 people dead.
It was sparked by the attempted capture of a top militant leader by the army.
“Yesterday we had a tragedy that involved our troops. A group of our military, Army men were hit by our own airstrike. We lost men, 10 killed and 8 wounded,” Mr Lorenzana told reporters.
President Rodrigo Duterte declared martial law on Mindanao island last week where Marawi city is located.
The Philippines military has since been using armed forces and helicopter airstrikes to try and drive the militants out of the city.