A five-week slide in average national petrol prices was halted this week by a 1.1 cent per litre rise, but experts say prices should soon begin to fall again.

CommSec economist Savanth Sebastian said this week that recent dramatic falls in the global price of oil should see petrol prices slide by another few cents.

"The Singapore unleaded price has slumped by almost $US8 a barrel in just over a week, a result that should ensure that petrol prices across Australia fall by around 3-5 cents a litre in a fortnight's time," Mr Sebastian told AAP.

He said that a continued drop in fuel prices should provide some improvement to household finances, with the average monthly fuel bill falling by almost $7 to $196 in the past six weeks.

"However a look at a longer timeframe shows that households are spending an additional $30 a month more on petrol compared with just over 10 months ago," Mr Sebastian added.

This latest report comes just weeks after CommSec Chief Economist Craig James said that prices "haven't got too much further to fall, limiting gains in confidence and spending capacity" for consumers.