Service station monitoring by the RACV has shown the majority of Melbourne’s service stations were selling unleaded at $1.55 per litre last week, roughly six cents higher than Warrnambool outlets during the same surveyed period.

However, south-west motorists were paying six cents more for unleaded than Melbourne drivers yesterday as the city price cycle gradually lowered.

RACV fuel spokesman Michael Case said the suburban price cycle used to have a weekly rotation but now lasted anywhere between a fortnight and three weeks.

He said it wasn’t certain that prices would rise before Christmas but the present cycle indicated it was likely to peak again around December 23.

“People in Warrnam­bool are probably used to buying petrol in Melbourne when they travel to the city because it’s usually cheaper,” Mr Case said yesterday.

“That isn’t always true. We’ve found that prices in Warrnambool and other regional centres can be cheaper than Melbourne on some days, dependant on what point of the price cycle we’re at.

“Last week was an example of that trend, where you had many service stations charging $1.55 in Melbourne while it was $1.48 in Warrnambool and Geelong.”

Supermarket giants Woolworths and Coles reached an accord with the Australian Competition and Consumer Commission last week over their long-running fuel discount voucher scheme.

The two major retailers agreed to limit petrol discount offers to four cents per litre, although further discounts can be made if the supermarkets fund the cost cutting solely through the petrol arm of their businesses.

“It’ll be one to watch when that agreement comes into force in January,” Mr Case said. 

“There’s no doubt it’ll provide some relief to independent retailers.”

British newspapers have suggested world petroleum prices will fall over the coming months due to the softening of economic sanctions against oil-producing Iran.