Firefighters from the ACT Rural Fire Service are working to controla bush and grass fire burning east of Potters Hill in Namadgi National Park.

The NSW Rural Fire Service has been notified and is preparing crews in the Bredbo area.

The bushfire alert and warning level has been set at 'advice'.

The fire is about 10 hectares in size and is out of control, heading in a south-east direction.

Classified as severe, the fire is expected to move quickly - particularly in today's dry and windy weather conditions.

Fires are categorised as 'severe' where there is a chance homes, businesses and lives could become at risk.

Emergency services advised homes would only offer safety if it and its residents were well prepared and could actively defend it during a fire.

"Leaving is the safest option for your survival. You should relocate to the location identified in your Bushfire Survival Plan," an ESA statement read.