Prices were as high as 166.9 cents a litre in parts of the state on Monday, according to the NRMA, which put the average price at 161.6 cents a litre.

CommSec economist Savanth Sebastian said the cost at the bowser had soared off the "double whammy" of the dollar and Singapore gasoline prices, which were at four-month highs of about $120 a barrel.

Mr Sebastian said prices would ease over the next week, but continue going up during the peak periods of the retail cycle.

"Over that early January period we'll probably see fuel prices over the next fortnight jump another two or three cents a litre," he said.

But Fueltrac's Geoff Potter said higher global prices off the back of instability in Libya, South Sudan and Syria accounted for a rise of only a few cents a litre.

Mr Potter blamed Coles and Woolworths for artificially inflating prices to offset the cost of their discount shopper dockets, which include offers that cut prices by more than 20 cents a litre.

The supermarket giants have given an undertaking to the Australian Competition and Consumer Commission to wind back their fuel discount offers to supermarket customers to 4 cents a litre from January 1.

But both companies rejected Mr Potter's claims.

"Petrol prices have started moving up, not at our instigation, and generally reflect higher oil prices internationally and the softening Australian dollar," a Woolworths spokeswoman said.

A spokesman from Coles said: "The increase in pump prices is the result of a range of global factors and something fuel retailers across the country are having to face."