The Buncefield oil depot supplies petrol and fuel oils for a large part of southeast England.
Oil is brought to the depot, near the commuter town of Hemel Hempstead, in an underground pipeline from tankers unloading on Britain's east coast.
Witnesses reported queues of people at petrol stations, waiting to fill up their cars, after the blast which spewed flames and a huge column of black smoke high into the sky on Sunday.
Sheila Williams, spokeswoman for oil giant BP, said there would be no problems with fuel shortages.
"There is certainly no shortage of fuel in and around the area and we are working hard to bring fuel supplies in from other terminals to petrol sites in those areas affected," she told Sky Television.
"Companies like BP can bring supplies via tankers from other areas," Williams said. "People shouldn't be concerned."
Police, who said they were treating the incident as an accident, also cautioned against panic buying.
"We have no indication at this stage that this explosion will cause fuel shortages," a Hertfordshire police spokeswoman said.
Area surrounding the depot were
also affected by the explosions
"We strongly advise against this as recent events have shown that panic buying alone can cause fuel shortages."
The depot is jointly run by oil companies Total and Texaco.
It supplies fuel to major airports including nearby Luton and London's Heathrow. But both said they held sufficient supplies to avoid any problems.
"There is no indication that there will be a shortage in the foreseeable future," a Heathrow spokeswoman said.
Luton said flights were taking off and landing as normal, although Heathrow said the pall of smoke could delay some services.
The main transport impact came from the closure of the M1 motorway which links south and north England and runs close to the plant.
Car-loving Britons have been edgy about petrol supplies since hauliers blockaded refineries in protest at fuel tax levels five years ago, and brought Britain to a virtual standstill.