Talks to prevent a four-day strike by tanker drivers who deliver fuel for Shell have ended without resolution, but will resume on Thursday.
Members of the Unite union representing more than 600 drivers met their employers to try to find a resolution to the pay dispute.
If their walkout goes ahead on Friday morning it will affect Shell's 1,000 forecourts across the UK.
The government has urged motorists not to panic-buy fuel, fearing shortages.
The talks took place at an undisclosed location and were being mediated by the conciliation service Acas.
The strike is due to start at 0600 BST on Friday and continue until 0600 the following Tuesday.
The Unite union says drivers' average pay, before overtime, of £32,000 has not increased since 1992.
But their employers, Hoyer UK and Suckling Transport, said the latest offer of a 6.8% pay rise would increase drivers' average salaries to about £39,000 a year.
Ray Holloway says motorists should "continue as normal"
Shell accounts for about one in every ten fuel stations in the UK and if the strike goes ahead the government has warned that some of them could run out of fuel.
A number of contingency plans are in place to minimise any disruption.
These include allowing companies to share information in order to get fuel to where it is needed in the event of a strike, while remaining within the scope of competition law.
The government also has the option of using a number of "emergency response tools" in the event of any disruption to fuel supply. These include:
The amount of fuel that retail customers are allowed to buy at any one time could be restricted
The supply of fuel could be prioritised to ensure adequate supplies to the emergency services and key services such as utility companies
Motorists could also be encouraged to use less fuel.
Shell is also understood to have a dedicated team working to minimise any disruption in the event of industrial action by maximising stocks of fuel and prioritising deliveries.
"They [the government] will be working with the fuel companies to ensure that if there are local problems, and they have admitted there might be, that they can be sorted out very quickly," said Mike Granatt, who was head of government communications at the time of the nationwide fuel protests in 2000.
The Petrol Retailers Association (PRA) has suggested the effect of a strike would be minimal, however, as long as customers do not panic-buy.
"The simple truth of this is that Shell is a big name brand, but it does represent only 10% of the fuel market in the UK. So there's no need for motorists to actually change their habits," said Ray Holloway from the PRA.
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