A collapse in global oil prices could see motorists buying petrol for $1 a litre, with the nation's competition watchdog arguing the benefits should be flowing to consumers within a fortnight.

Oil prices have fallen 28 per cent since Friday to around $US34 a barrel after the global oil cartel OPEC in effect broke down. Prices had already fallen because of the coronavirus outbreak, which has sharply dented demand from China due to its broad economic slowdown.

Petrol prices could fall as low as $1 a litre on the back of the collapse in global oil prices. Credit:AAP

Treasurer Josh Frydenberg said on Monday he had talked to the Australian Competition and Consumer Commission about ensuring the drop in wholesale prices was delivered to consumers at the bowser.

"They have assured me that they will not only maintain their monitoring role and the vigilance that that involves, but they'll also be calling out any energy companies that don't pass on the reduction in the wholesale price to the Australian consumer," he said.