A probe by the consumer watchdog into high petrol prices in Cairns is long overdue, Queensland's peak motoring body says.
The Australian Competition and Consumer Commission (ACCC) on Tuesday revealed the far north Queensland city would become the fourth location for a petrol price investigation.
The average unleaded petrol price was 146.4 cents per litre (cpl) in 2014-15, which was 12.3 cpl higher than prices in major cities including Sydney and Brisbane.
"Understanding why petrol prices in Cairns are so high will help us identify the steps that could be taken to increase transparency and promote competition in the Cairns' fuel market," ACCC chairman Rod Sims said.
"It should also provide some explanation of why petrol prices are high in other regional locations around Queensland."
RACQ spokesman Michael Roth said the study would be welcomed by Cairns motorists who have been ripped off for years.
"We're hopeful this study will make a real difference to ULP prices in the area," he said.
"When a market study was carried out in Darwin prices dropped, and they remain significantly lower now than they were prior to that study."
State Main Roads Minister Mark Bailey said the ACCC had the tools and expertise to bring "real scrutiny" to the Queensland market.
"As we have seen in recent weeks, Cairns, in particular, regularly experiences more expensive petrol prices than its neighbours which is unfair for local motorists," Mr Bailey said.
"We need to be satisfied that market prices are fair and reasonable wherever you live in Queensland, and this ACCC investigation is a positive step forward."
The federal government tasked the ACCC with monitoring petrol prices, costs and profits in December 2014 and it has so far looked at the markets in Darwin, Armidale and Launceston.
