Last-minute talks to avert a fuel strike are being held as 500 petrol tanker drivers prepare for a four-day walkout.
Members of the Unite union employed by two firms working on Shell contracts are due to walk out from 6am on Friday until 6am the following Tuesday, in a pay dispute which could hit one in 10 filling stations across the UK.
The Government has urged drivers not to panic-buy fuel amid fears of petrol shortages.
A Downing Street spokesman said: "We want the public to continue to buy as normal so as to avoid creating problems that might otherwise not exist."
Contingency plans include allowing suppliers to share information about stocks without falling foul of competition laws.
Fuel supplies to the emergency services would also be maintained in the event of shortages.
In a last-ditch attempt to avert strike action, talks led by conciliation service Acas are being held at a secret location.
The pay row has erupted because members of Unite claim they are paid the same now as they were in 1992, just under £32,000 a year, despite their working week being 11 hours longer.
Unite repeated its call for Shell to get involved in the dispute and stop "sitting on its hands.".
However, the petrol giant is refusing to get involved and renewed calls for the two sides to resolve the dispute.
