The army is on standby with soldiers at “increased preparedness” to help deliver fuel if needed, the defence secretary has said.
It comes after long queues continued in many places on Monday after drivers apparently ignored pleas to stop panic-buying.
Army tanker drivers will now receive specialised training ahead of any possible deployment.
“The men and women of our armed forces stand ready to alleviate the transport pressures where they are felt most,” said Defence Secretary Ben Wallace.
“That is why I have authorised their increased preparedness so they are ready to respond if needed.”
Business Secretary Kwasi Kwarteng issued the Military Aid to the Civil Authorities (MACA) request, the mechanism for armed forces to lend support.
He said the fuel industry expected demand to return to normal “in the coming days”, but that “it’s right that we take this sensible, precautionary step”.
“The UK continues to have strong supplies of fuel,” he added.
“However we are aware of supply chain issues at fuel station forecourts and are taking steps to ease these as a matter of priority.
“If required, the deployment of military personnel will provide the supply chain with additional capacity as a temporary measure to help ease pressures caused by spikes in localised demand for fuel.”
Transport Secretary Grant Shapps has also authorised an extension to ADR driver licences, which allow drivers to transport goods, such as fuel.
It will apply to licences expiring between 27 September and 31 December, and extend their validity until 31 January 2022.
“Extending ADR licences will further help ease any pressures on fuel drivers by removing the need for refresher training courses and ensuring they can keep providing their vital service on our roads,” Mr Shapps said.
Petrol retailers had been hoping for a return to normal after motorists drained pumps over the weekend.
But there was little sign of panic-buying diminishing on Monday.
A joint statement from BP, Shell UK, Esso Petroleum/ExxonMobil, Wincanton, Certas Energy UK, Hoyer Petrolog UK, Greenergy, Fuels Transport & Logistics, Downstream Fuel and Suckling Transport urged drivers to buy fuel normally.
It said: “There is plenty of fuel at UK refineries and terminals, and as an industry we are working closely with the government to help ensure fuel is available to be delivered to stations across the country.
“As many cars are now holding more fuel than usual, we expect that demand will return to its normal levels in the coming days, easing pressures on fuel station forecourts. We would encourage everyone to buy fuel as they usually would.
“We remain enormously grateful to all forecourt staff and HGV drivers for working tirelessly to maintain supplies during this time.”
The panic-buying has led to industries from taxi drivers to the meat processing sector – and even non-league football – facing difficulties and prompted calls for health workers to get priority.
The British Medical Association said there was a real risk that some would not be able to get to work.
And the Unison union called on ministers to use emergency powers to “designate fuel stations for the sole use of key workers” – a call backed by the Royal College of Nursing.
“The Government has to take control. It’s no good ministers wasting time on a pointless blame game or pretending there’s no problem,” said Unison general secretary Christina McAnea.
“Essential staff must be able to get to their jobs so they can continue to provide the services so many rely upon.”
The Petrol Retailers’ Association (PRA), representing two-thirds of all UK forecourts, said that with many drivers’ tanks now full it was watching for an “easing of demand”.
The crisis mushroomed after the disclosure last week that a small number of petrol stations had seen supply disrupted due to the nationwide shortage of HGV drivers.
Some retailers, such as Asda and EG group, have been restricting sales to £30 a time.
Even if the frenzy does abate, motorists could face another headache as the price of Brent crude oil continues to climb.
It hit a three-year high of just under $80 a barrel on Monday – likely to lead to higher prices at the pumps.