Australia's competition watchdog is to ask the country's major oil companies to explain why petrol prices soared on the eve of the Easter holiday - one of the busiest times of the year for motorists.
Prices rose by as much as 10% last week ahead of the four-day break, angering motorists and politicians who accused the oil companies of collusion.
Australian Competition and Consumer Commission chairman Allan Fels said there seems to be no "reasonable excuse" for the price rises as world crude oil prices are relatively stable.
Mr Fels said that oil companies might have "taken advantage of motorists at a vulnerable time".
He commented: "We'll apply the law if we find any evidence of communication between oil companies before the price hikes."