The advice was given as it became apparent there was an increasing rush to buy fuel across the city as more stations were forced to close their pumps.

The union was today threatening to escalate its action after a breakdown of peace talks.

There are no plans to resume talks before the strike is due to start at the weekend.

The larger supermarket petrol stations were adamant contingency plans were in place and that there was no need for panic.

A spokesperson from Sainsbury’s said, “Availability and supply is still good. We’ve only got 12 forecourts in Scotland, which is probably fewer than some of the others.

“We are seeing an uplift in demand, but we are asking people to listen to the message given by the AA and asking people not to panic. There are contingency plans in place.”

The supermarkets were also continuing to secure and receive deliveries.

Asda Milton received a delivery this morning and was preparing to get its pumps operating again after closing the filling station temporarily after their delivery tanker broke down en route.

“The message to motorists is still very much not to panic buy because we have plenty of fuel available. Asda does not source its fuel from the Grangemouth refinery so the strike is not a problem for our filling stations anyway. It is business as usual,” a spokeswoman for Asda explained.

Morrisons also sources its fuel from other locations and they were continuing to serve motorists without any problems.

A Tesco spokesperson said, “Sales are still higher than normal. We are replenishing forecourts as quickly as possible and, in common with other Scottish fuel retailers, are working hard to minimise any disruption to supplies.”

The “not-knowing” when the next load would arrive was concerning some of the smaller petrol stations.

A spokesperson from Forfar Road Service Station said, “Our supplies are quite low. We have a tanker here just now, but we are only getting half a load.

“According to how things have been going, I’m really not sure how long it’s going to last.

“We have two tankers ordered for Saturday, but we’ve really no idea what’s in the pipeline so we’re just going to have to wait and see.

“It’s a mix between public panic and lack of supply and it seems like it’s just going to get worse.”

A spokesman for Scott Fyffe garage on the Kingsway East said, “We have no fuel at all and the station is closed until we get supplies. We are hoping to get a delivery later today.

“The station ran out last night after a busy few days of people panic buying.”

The Shell Discovery station in East Marketgait remained closed to fuel customers for a second day today. The 24-hour garage coned off all its pumps by 10pm on Tuesday night after a £15 limit failed to sustain their fuel supplies.

Cari Edwards, supervisor at the station, said, “We have still not had any fuel deliveries and we have had no word of when a delivery is due. We have been chasing them up for supplies, but to no avail.

“This station is independently owned so we are not a priority station.”

BP Kingsway this morning said it still had supplies of unleaded, but was running short on diesel. However, staff at the petrol station were not sure if its supplies would last throughout the day.

n Up to 1200 workers at the site will walk out at the Grangemouth site on Sunday and Monday in a bitter row over plans to end their final salary pension scheme for new entrants and to make other changes.

The site’s owner, Ineos, accused the Unite union of rejecting proposals to avert the action, which will lead to the closure of the site from Saturday.

The union’s chief negotiator said today officials would now consider escalating the industrial action.

Phil McNulty said he “deeply regretted” any fuel shortages for motorists as a result of the strike, but he maintained the union had done everything it could to resolve the row.

Unite maintained that the company was still insisting that the final salary pension scheme would close to new workers, which had been rejected by the workforce.

The company was still planning to make other changes to the pension scheme which Unite objected to, said Mr McNulty.

Talks at the conciliation service Acas broke down last night, although both sides said they had reached an agreement that would maintain the safety of the site and the integrity of the plant for the duration of the dispute.

Ineos said safety was now a top priority and it would ensure Grangemouth was safe throughout the dispute following an agreement with the union that will see supplies continue for emergency services.