The warning follows another car fire over the long weekend that takes the total number of vehicles deliberately burnt in the territory since the start of last year to 136.

Police said the firebombing of a silver Holden Statesman in the car park of the Raiders Sports Club at 1.25am on Australia Day was ''a very un-Australian'' act.

Many of the cars that have been torched over the past 13 months had been stolen and, according to ACT Policing statistics, car thefts are on the rise across the territory.

''A yearly analysis of the crime statistics indicates most offences are continuing to trend downwards in the ACT, when compared with 2011,'' an ACT Policing spokesman said last week.

''Only motor vehicle theft and road collisions with injury are up, increasing 12.5 per cent and 1.8 per cent respectively.''

ACT Policing has yet to respond to a Fairfax Media inquiry last Thursday for details on how many of the car thefts and fires reported last year were successfully resolved.

Australian Bureau of Statistics figures for 2010 indicate that only 7.1 per cent of ACT car theft investigations were resolved within 30 days.

This was the lowest rate in the Commonwealth and compared to 14.3 per cent in NSW, 24.2 per cent in Queensland and 28.5 per cent in Tasmania.

ACT Fire and Rescue warns that regardless of the cause, people should exercise extreme caution when approaching a burning motor vehicle.

A spokesman said that when a car caught fire, either through an act of arson or from other causes, the blaze generated toxic smoke and extreme heat. There was also the risk of explosions from fuel tanks, tyres and items inside the vehicle.

Our advice ''is to call 000 and report [it] to the fire service'', the spokesman said.

''Stay a safe distance away, avoid inhaling smoke [and] if you have access to a water supply try and prevent items in the vicinity of the vehicle catching alight by cooling them.''

Fairfax has been told of incidents where vehicle tyres have been slashed to stop cars from being pushed away from houses and hoses have been stolen or tossed into the flames to make it harder to protect property.

Victims have said they believe the offences are often the work of juvenile gangs who roam the streets late at night and in the early hours of the morning.

ACT Policing said the owner of the car burnt on Australia Day had left her vehicle at the club after dining with her partner.

''ACT Fire and Rescue determined the fire was started on the front seats and was deliberately lit,'' a spokesman said.

Arsonists also lit a grass fire in bushland in Fadden late on Friday night.