Petrol prices have hit fresh record highs, new data from the Australian Institute of Petroleum shows.

A leading petrol expert has tipped prices to rise as high as $1.75 within a fortnight.

The national average price for unleaded fuel was now a record $1.58 a litre, the institute's weekly update issued today said.

Darwin was doing it toughest in the capital city averages, with motorists in the Northern Territory paying $1.68 a litre.

CommSec equities economist Savanth Sebastian said there was no sign of the pain easing.

"The national average price is likely to hit $1.60 a litre, with prices likely to lift as high as $1.75 a litre in the next fortnight," Mr Sebastian said. ... Read full article