Petrol prices have risen for a fifth straight week to an average $1.52 per litre, on the back of a weak Aussie dollar and despite oil prices stabilising around $US100 ($A120.15).

Fresh data from the Australian Institute of Petroleum shows the national average price of unleaded rose by 0.4 cents to 152.4 cents a litre in the week ending September 21.

Because oil is traded in US dollars, the strengthening Greenback has hurt Australian motorists who stood to benefit from the slide in oil prices.

“Crude oil prices have come off sharply but so has the dollar,” NAB energy economist Gerard Burg said.

Commsec equities economist Savanth Sebastian backed Burg’s interpretation.

“Australian motorists are unlikely to see major changes at the petrol pump over the next fortnight,” Sebastian said in a briefing note.

“While world oil prices continue to slide, the Australian dollar has also continued to soften, neutralising potential savings for motorists.

“The national average petrol price is likely to remain around the $1.50 level for the next few weeks.”

Burg said the price of oil, light, sweet crude for October delivery was up 35 cents to $US104.90 ($A126.04) a barrel in electronic trading on the New York Mercantile Exchange midday in Singapore, was being carried by fundamentals.

“I think oil prices are pretty much justified at the moment in terms of fundamentals in the market,” Burg said.

“The sharp decline we saw into the low one hundreds was really more about the financial market pressures rather than actually crude oil fundamentals.”

He said a price between $US100 ($A120.15) and $US120 ($A144.18) was justifiable.

If the Aussie dollar had remained close to parity with the Greenback, as it was earlier in the year, Sebastian said it would amount of about a 20 cent saving for drivers.

“The average Australian household is forking out almost $213 a month on petrol, a saving of $16 from the highs set in mid July,” Sebastian said.