TWO grass fires at the rear of Amaroo School are believed to have been deliberately lit.

At about 3.20pm on Wednesday, police and firefighters responded to reports of two grass fires between Amaroo School and Horse Park Drive, Amaroo.

The fires caused damage to a section of grassland, a perimeter fence and the district playing fields.

Multiple ACT Fire and Rescue units responded to extinguish the fires and police are now seeking public assistance to determine the cause of the fire.

Anyone who may have information about the fires should call 1800 333000 or via the Crime Stoppers ACT website.