Thieves hit Canberra petrol outlets more than 1100 times in the nine months to April 30, compared with about 700 in the corresponding period in 2006-07.

A police spokesman confirmed yesterday the 33 per cent increase made petrol rip-offs the ACT's fastest growing crime, bucking the general trend of a decrease in property crime rates in Canberra.

A police survey of the ACT's 56 service stations showed about 20per cent of outlets were asking motorists to pay before they filled up during the hours of darkness or were closing outlying bowsers at strategic times in a bid to foil the petrol bandits.

The thieves often fix false number plates to their cars and The Canberra Times reported in May that the theft of number plates had reached the level of 75 incidents a month.

The Territory and Municipal Services' register of stolen plates, distributed monthly to service stations, recorded 101 plates stolen in July.

ACT Motor Traders Association and service station owners' spokesman Peter Taylor said the offender profile had altered as unleaded prices came down from their all-time highs, but drive-offs remained a serious problem for the industry.

''You still have the deliberate hard-core offenders of the drive-offs but the thefts by opportunistic thieves have eased slightly,'' Mr Taylor said. ''The sort of people who are willing to undertake this sort of crime are out there doing other things, of course.''

Mr Taylor said the industry was reluctant to make all drivers pay before they filled up their vehicles and he was hopeful that other solutions could be discussed at October's forum.

''So this discussion with the police will be what measures we can put in place,'' he said.

''It's pretty draconian to have an enforced pay-before-fill system, it doesn't give a good example of the state of the town if that's the way you're forced to do business.''