The government is preparing to flood the market with an extra 800 million litres of petrol and diesel in a bid to fix supply shortages plaguing some regional areas.
Between late February and mid-March, average petrol prices have shot up nearly 50 cents a litre across Australia's five largest capital cities, according to the consumer watchdog's first weekly report on the fuel market since the start of the war.
Petrol wholesalers and retailers appeared to increase prices almost the same day as the war broke out, despite price changes usually taking at least a week to flow through the supply chain, the Australian Competition and Consumer Commission said.
"In this case it looks like petrol retailers increased prices at the pump when they were selling fuel they had bought before the conflict at cheaper prices," ACCC commissioner Anna Brakey said in a statement.
"Retailers must explain to the Australian public why they did not follow their usual practice, and when they will reduce prices in line with any reductions in wholesale costs."
The price of petrol at the bowser rose more 18 cents a litre faster than wholesale costs, the ACCC said.
The agency wrote to companies including 7-Eleven, Ampol, BP, Chevron, Mobil, United Petroleum, Viva Energy and EG Australia last week, seeking urgent information about their recent price increases, and will meet with them next week.
Energy Minister Chris Bowen announced plans to release up to 762 million litres of petrol and diesel from companies' emergency reserves to help tackle shortfalls in regional areas.
But the extra fuel would not flow immediately because of supply chain complexities, he said.
"It's not like they can just press a button and get fuel out the door, but it will make a difference going forward," he told reporters in Sydney on Friday after the government's National Security Committee met.
Mr Bowen said supply and price issues were being driven by panic-buying motorists, not a lack of fuel coming in from overseas.
"I ask Australians, buy as much fuel as you need: no more, no less," he said.
"I've seen (people) on Facebook marketplace filling up jerry cans, Bunnings running out of jerry cans ... going on Facebook marketplace, selling fuel at inflated prices - that is un-Australian.
"It's dangerous. It shouldn't be done."
Australia was "nowhere near" running out of fuel, Mr Bowen said.
Fuel imports remained steady but some stations had less than 24 hours' worth of petrol on hand, Australasian Convenience and Petroleum Marketers Association chief executive Rowan Lee said.
"They're running trucks throughout the night,'' said Mr Lee, whose body represents petrol stations, distributors and wholesalers across the nation.
"They're trying to just keep their system going."
He told AAP the government's plan to release more fuel from domestic reserves was welcome, but it was unclear how long it would take to flow through to motorists.
The government has also relaxed quality standards for the next 60 days, allowing the use of fuel with higher sulphur levels, to boost the domestic market by 100 million litres of petrol per month.
Quality levels would remain very high by international standards, the government said.
Opposition energy spokesman Dan Tehan said the government should consider easing diesel quality standards.
"Australia's economy runs on diesel," he said.
Mr Tehan accused Mr Bowen of deploying ad-hoc measures in response to the supply and price crunch.
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