Hopes for a breakthrough in the Grangemouth oil refinery dispute rose last night, but ministers were preparing for a fresh confrontation with the road haulage industry as the £5 gallon of petrol became a reality at the pumps.

Fuel protests returned as hauliers demanded help from oil companies and the Treasury, which is raking in huge surpluses from record petrol prices. The cost of filling an average car could reach £84 next year, one consumer body will say today.

Air passengers are also being hit as British Airways announced that it was slapping fuel surcharges on all tickets from Friday to offset the escalating cost of fuel. Long-haul passengers can expect to pay an extra £30.

The two sides in the Grangemouth dispute said yesterday that they had agreed a proposal that could end an impasse that has threatened to cripple the Scottish economy and caused the Forties pipeline, which supplies more than a third of Britain's oil, to be shut down.

Although no details were released of the contents of the proposal, a joint statement issued after hours of talks between unions and management at a secret location in London said it would now be considered by the Ineos company, which owns Grangemouth, and the Unite trade union.

The news that the two sides may be on the brink of a deal is the first good news in a bitter dispute in which some petrol stations in Scotland have run out of supplies and 65,000 tonnes of emergency fuel has been supplied to Grangemouth from European ports.

Twelve hundred workers at the refinery returned to work yesterday after a 48-hour walk out at plans by Ineos to close its final salary pension scheme to new entrants.

John Hutton, the UK Business Secretary, held talks on the dispute with First Minister Alex Salmond at the Scottish government headquarters in Edinburgh yesterday. Mr Hutton said that he had come to voice his

“appreciation and respect” for work by the Scottish government to minimise the dispute's impact.

Meanwhile in Central London about 250 lorries caused disruption evoking memories of the refinery blockades of September 2000. Further protests are to be staged by hauliers and farmers around the country as campaigners try to keep the issue in the public eye.

A spokesman for Transaction-2007, which organised yesterday's protest, said: “Any further rise in cost of fuel will be an obvious trigger. We need to keep the issue alive and win support from ordinary motorists.”

As hauliers demanded immediate financial help, BP and Shell announced combined profits of £7.2billion in only three months. Soaring prices are also delivering unexpected surpluses for the Government in the form of higher tax revenues from North Sea oil. If prices remain at current levels, the Treasury could receive as much as an extra £2.5 billion.

Vince Cable, the Liberal Democrats' Treasury spokesman, said that Gordon Brown would be “quietly delighted” as the oil tax revenues fill depleted coffers.

Mr Cable, a former chief economist at Shell, said that Chakib Khelil, president of Opec, had been right to give warning that the oil price could reach $200 a barrel. “There's the potential for a major oil shock on top of what we have today,” Mr Cable said.

Roger King, chief executive of the Road Haulage Association, called for a windfall tax on the leading oil companies or from the Government's own profits from extra VAT on fuel, and urged the Chancellor to scrap the deferred 2p rise in fuel duty.

Mr Hutton warned those planning disruption that the Government was ready to defeat any attempts to disrupt supply.