Fuel tanker drivers have rejected a proposed deal aimed at averting strikes, renewing the threat of walk-outs, Unite said on Wednesday.
The union's assistant general secretary Diana Holland told journalists that they were still "optimistic" and talks aimed at averting industrial action would continue.
She said: "While there has been some progress it is clear that our members need more guarantees and assurances from the employers about their commitment to meaningful minimum standards.
"We remain committed to achieving a negotiated settlement that brings stability and security to a vital industry and gives this workforce, and the public, confidence that the race to the bottom is ending."
"What we can say to people is please, as we have said all along, do not panic. It is very clear at this point in time we are not on strike.. We are still wanting to talk and we are calling for further talks because we feel we are able to reach a solution in this dispute."
Scroll down for a gallery of images revealing the chaos and panic-buying which occurred as the threat of strike loomed
She added: "We are going to approach Acas for [further] talks. There will be a range of discussions."
Energy and Climate Change Secretary Ed Davey said the government was "disappointed" no agreement had been made.
“We understand that these are complex issues but urge both parties to work towards a negotiated resolution with the support of Acas.
“The government continues to believe that any strike action would be wrong and unnecessary.”
According to the union drivers "overwhelmingly" rejected a deal offered after six days of talks with the conciliation service Acas.
Peter Harwood Acas Chief Conciliator said they were "disappointed" but would try and facilitate further talks: "Naturally, we are disappointed at today's outcome, following the parties' intensive talks at Acas over the last two weeks. We are contacting the parties and the challenge now is to see if we can find a way forward."
A government spokesperson said on Friday evening they were continuing " "to work on contingency plans" in event of any strike.
Fuel tanker drivers are concerned about health and safety, pensions and terms and conditions.
The announcement came just hours after Prime Minister David Cameron and Labour leader Ed Miliband clashed in the House of Commons over the threat of a tanker strike.
Cameron accused the Labour leader of "complete weakness" for failing to stand up to Unite, while Miliband called on the PM and Cabinet Office minister Francis Maude to apologise for provoking panic-buying at the pumps when the prospect of a strike was first raised.