Flags fluttering, the strike began at 6am with a group of silent workers leaving the massive refinery through gate four and holding aloft red and white flags.

Yesterday that calm atmosphere appeared to be reflected at the pumps, with little sign of panic-buying. Aside from some localised shortages in the north-east of Scotland, the vast majority of forecourts had supplies of fuel.

Yet there was little sign of any common ground between the strikers and management at the Grangemouth refinery.

The Unite union's Pat Rafferty said the mood was one of disappointment and anger.

The senior regional industrial organiser said: "The company is trying to make one key change to the pension scheme and that's to close it on August 1. What that means for the existing workforce is that the pension scheme in its current form will wither and die in time.

"It also means that the sons and daughters that are coming, and future generations, will not have the same pension provisions as the current workforce. It's about trying to protect the future generations as well as trying to protect the present."

The workers held A4-sized placards with the slogan "Scotland's workers deserve better. Michael Connarty, MP for Linlithgow and East Falkirk, and Cathy Peattie, MSP for Falkirk East, addressed the rally.

Striking Grangemouth supervisor Colin McLean said: "Before Ineos took over, I was with BP for 27 years. Basically we're sick - we transferred our pensions in good faith into their pension scheme."

Another worker said: "We're feeling disappointed that we're having to take this action.

"We're very reluctant to do so. At this point the company has not made any efforts to set up any meetings to discuss the issue of pensions.

"We have meetings to talk about safety issues, integrity issues and fuel supply to energy and life-critical services. So for the only actual issue causing this dispute, there are no plans (to meet)."

Ineos executives and Unite leaders' stance appeared to draw back from earlier harsh rhetoric to a degree yesterday, but a solution still seemed distant to workers.

As the dispute continued, contingency measures introduced by both the Scottish Government and Westminster were brought into action to help ensure supply continues to flow.

Around 65,000 tonnes of fuel was due to be shipped in from European ports, including Rotterdam and Amsterdam, to supplement reserves.

Supplies were due to arrive at Grangemouth and Aberdeen, but Unite had said its workers would only unload fuel for the islands and emergency services.

The extent of the strike is such that it has already forced BP to close off the Forties Pipeline System, which brings in 700,000 barrels of oil a day from the North Sea to BP's Kinneil plant, which is powered from the Grangemouth site.

Energy industry group Oil and Gas UK said the action could cost the UK economy £50m a day in lost production.

Malcolm Webb, its chief executive, said: "Around 80 companies and their operations are now caught up in a situation which has nothing to do with them and which should have been avoided."

The main effects of the walkout were likely to be felt by the Treasury - which relies heavily on tax from oil production - and drivers at petrol stations, some of which limited purchases in anticipation of the strike.

Motorists were again urged not to hoard fuel, as government north and south of the Border moved to avoid a repeat of scenes in 2000 when drivers were forced to line up at garages as truckers, angry at heavily taxed fuel, brought Britain to a standstill by blockading refineries.

John Hutton, Westminster Business Secretary, said: "There is plenty of petrol and diesel in Scotland to meet demand during this period of time. But of course there is going to be a challenge if people change the way they consume fuel."

First Minister Alex Salmond said: "There is a job to do to keep Scotland moving and we are absolutely focused on that. In the meantime, all of us can help maintain supplies by acting responsibly."

Douglas Robertson, of the Scottish Motor Trade Association, said that while there was some panic-buying earlier in the week as the strike loomed, drivers appeared to be taking heed of assurances.

However, some petrol stations in and around Edinburgh were limiting purchases to £20, and lines of cars formed beside pumps.

A number of stations reported they had run out of diesel, while prices at the pumps had risen to as much as £1.25 for a litre of unleaded petrol, up from about £1.08 last week.

However, government is bound to ensure that supplies are always in reserve to last the country at least one week, and there was no indication that rationing would be introduced.

Lothian Buses, which said last week that services would cease after last night if it could not access more fuel, confirmed yesterday it had a received a delivery on Friday.

However, should the crisis escalate and more lengthy periods of industrial action ensue, the Ministry of Defence could be deployed as last resort. Fire, police and ambulance services would be prioritised should emergency measures be introduced.

Under such plans, designated petrol stations would serve police fire and ambulance services. Others would provide fuel for key distributors such as food hauliers.

Canonmills Garage in Edinburgh, which had no diesel yesterday, is nominated for emergency services use.

An attendant said: "Because we are designated to the emergency services, if rationing was brought in the police, ambulance and fire vehicles would take priority."

As well as limiting amounts to individuals, the government could also take broader control of bulk distribution to large users such as schools, hospitals, prisons and airports.

A spokesman for Lothian and Borders Police said: "The force has its own fuel supplies and there is currently ample in storage to cover the proposed duration of the walkout. We are also working with partner agencies to ensure there is no interruption to any essential services should any shortage in supply develop."