ACT Fire and Rescue and the ACT Rural Fire Service fought the flames, and a bulldozer was used to dig a containment line around the fire to prevent it escaping the burnt-out area. By about 7.45pm the fire had been extinguished, but two tankers patrolled the site through the night to ensure there were no flare-ups.

The latest Canberra fire comes as temperatures across the Territory and NSW are set to rise again, increasing fire risk.

Across NSW on Tuesday afternoon, about 800 fire firefighters were battling 100 bushfires across NSW, 25 of them uncontained, with more than 500,000 hectares of the state now burnt in 11 days.

The worst of the fires, at the Warrumbungle National Park near Coonabarabran in the state's north-west, has so far burnt through 40,000 hectares, and remains out of control, the NSW Rural Fire Service says.

Around 155 firefighters from greater Sydney, the Hunter region and other parts of the north coast arrived on the scene on Tuesday so they could rotate crews to manage fatigue, with some firefighters working 36-hour shifts. About 180 firefighters were fighting the fire at 4pm, the RFS said.

The Acting Premier, Andrew Stoner, who toured fire-ravaged areas around Coonabarabran on Tuesday said the blaze had caught everyone by surprise.

''It's absolutely obvious that this was an extreme fire and that the ferocity and the rapidity of this fire caught everyone pretty much unawares,'' he said. ''It's absolutely amazing that there hasn't been more property damage as a result of this fire.''

He predicted the fires would continue, with temperatures to reach over 40 degrees on Thursday and Friday in much of NSW. with AAP