More than 20 firefighters battled a grass fire just north of the ACT this afternoon.

Just before 2pm ACT and NSW Emergency Services responded to reports of a grass and structure fire on Duke Road near the ACT/NSW border.

Upon arrival firefighters located a grass fire about 200m x 100m in size and spreading.

Fire crews from ACT Fire and Rescue, Fire Rescue NSW and NSW Rural fire Service responded to the scene.

The fire was contained just before 4pm this afternoon with no significant damage to nearby structures.

The cause of the fire is believed to have been from a fault in a solar power system.

There were no reports of injury.