The rusty green fuel trailer hardly looks like it is worth stealing. But some time before 1 March it was hooked up to the back of a vehicle and taken from a property at Huntley, south of Orange, in the New South Wales central tablelands.

It was just another in a series of thefts that police across Australia are keeping a watchful eye on.

The tank contained 800 litres of diesel. Since the bombing of Iran on 28 February, the price of diesel has climbed towards $3 a litre in some places, with the price of unleaded not far behind.

Growing fuel prices and fears of shortages are expected to increase thefts from service stations and farms, police have warned.

In South Australia, the police commissioner even flagged that officers might stop investigating “drive-offs” at service stations, unless retailers installed prepaid pumps. It came amid an increase in petrol thefts this month, including from first-time offenders, Grant Stevens said.

“This takes police away from other responsibilities that we could be attending to, so we are calling on the retail fuel industry to take positive steps to prevent this virtually overnight by implementing prepaid, which is something they have within their capacity to do,” the police commissioner told the ABC.

“We have seen reports of this type of crime for years, or probably decades, and I know that I have been agitating for years to see something more proactive from the industry.

“If you were foolish enough to leave your TV out the front of your house every single day, and have it stolen, there would come a point in time where we’d say: ‘we’re not taking a report from you for that’.”

His comments were swiftly rebuked by industry groups, who said prepaid pumps could cost $5,000 each, a cost that would be passed on to consumers.

In a statement, SA police said there had been 221 fuel theft offences reported in the week ending 15 March, 59 more than the previous week. Ninety seven of these involved first-time offenders.

The Western Australian police commissioner, Col Blanch, this week said he was expecting an increase in fuel theft driven by “fear of the unknown”.

“We do see fuel theft outside of times like this, but certainly the motivator for more fuel theft now will be … that anxiety and that fear of the unknown, of what’s going forward and the availability of fuel,” Blanch told ABC radio.

“But what people would really be doing is just stealing it from someone else who is in the exact same circumstance as you, has the same fears, the same anxiety, has the same cost pressures, so I’m not sure that contributes to a better outcome if you steal someone’s fuel.

“You can get charged for it, it can ruin your life, you can go to prison, all of those things can happen … you might say ‘but you know, I needed the fuel because I thought I couldn’t buy any in the future’ – that’s not going to be a reason that you can avoid court.”

Police patrols have increased in the state’s wheatbelt region to deter would-be thieves.

Aside from the theft at Huntley, NSW police are also investigating the theft of about 500 litres of diesel from a grain storage facility in Nyngan, which was reported on 11 March.

Acting Det Insp Andrew Maclean last week warned NSW farmers to expect an increase in fuel thefts.

“Landholders are asked to remain vigilant around their on-farm fuel storage and police encourage installing surveillance cameras, securing bowser handles with padlocks, and keeping detailed records of all fuel usage,” Maclean said.

Police in NSW, Victoria and Queensland were unable to provide statistics on the number of recent thefts, but all noted they were remaining vigilant, including in regional areas.

However, Tasmanian police said there was no pattern emerging of increased fuel theft; there were 44 reported cases in the past six weeks, but the most cases – 11 – were reported in the week before the conflict started.

ACT policing said it had not noted an increase in fuel thefts, with only six reported this year, and no cases of siphoning, though a spokesperson noted such offences were underreported.