Oil companies will today be given “one last chance” to pass on price cuts to motorists — or face Government action, according to a report in today’s Sun newspaper.

The report says Transport Secretary Justine Greening has ordered officials to draw up a code of conduct in order to shame retailers out of over-charging, which she will enforce unless companies start delivering cheaper fuel “in days”.

The Sun said Ms Greening’s department is also devising a new price register so consumers can go online to find the cheapest petrol and diesel — and see who is ripping them off. The Cabinet minister is quoted as saying: “Petrol prices go up instantly when wholesale prices rise, but when wholesale prices fall it can take weeks for them to come down again.

“It is indefensible that motorists should be ripped off. It’s time the big companies started playing fair with the motorist, so I am giving them one last chance.”

The newspaper said petrol giants are buying stocks for 10p a litre less than in April thanks to a fall in global oil prices, but have outraged drivers by passing on just 7p of the price cut at the pumps — pocketing the rest.