Unite has been given an extension to a deadline for declaring strikes in the fuel tanker drivers dispute so that peace talks can continue.
Under employment law, the union should have made a decision by late afternoon on whether to call its 2,000 members in the industry out on strike after they voted last month for industrial action.
Talks have been held all week between the union and officials from six distribution companies involved in the row over a number of issues, including terms and conditions and health and safety.
Acas chief conciliator Peter Harwood said: "I am pleased to announce that it has been agreed by the contractors and Unite to extend the validity of the ballot period until next Friday, April 20, and talks will continue this evening.
"The intention is that no notice of industrial action will be given during that period."
Mr Harwood has described the talks as a "complex process", adding that all parties remained committed to securing a positive way forward.
The dispute has been brewing for more than a year but flared up last month when Unite announced that workers in five firms had voted to strike.
There was a spate of panic-buying of fuel by motorists last month after the Government advised them to top up their tanks because of the threat of a strike.
Chaotic scenes and long queues were seen at garages across the country following the Government's advice, which was heavily criticised.
Labour led calls for the resignation of Cabinet Office minister Francis Maude for advising motorists to store jerry cans of fuel in their garages.
Unite will have to give seven days notice of any industrial action.
A Department of Energy and Climate Change spokesman said: "We welcome the news that both parties are continuing the talks at Acas to resolve the dispute.
"We hope that both sides will remain committed to reaching a negotiated settlement and that positive progress can be made.
"The Government continues to believe that any strike action is wrong and unnecessary.
"We will continue to work on contingency plans to increase the country's resilience in the event of a strike."