The competition watchdog will keep a close eye on service stations and petrol suppliers to ensure Australians are not treated as "mugs", Treasurer Jim Chalmers says.
Drivers already face soaring prices at the bowser but there are fears they could spike more than 20 cents a litre as the fuel excise cut, which has been in place for the past six months, ends on Wednesday night.
Dr Chalmers said he spoke with the Australian Competition and Consumer Commission on Wednesday morning.
