Fuel supplies in northern England, Scotland and Northern Ireland could be disrupted if a strike at an important oil refinery goes ahead later this week.
More than 1200 workers at the Grangemouth refinery in Scotland are threatening to strike this week in a dispute over pension payments.
The Ineos-owned refinery supplies fuel for much of Scotland, northern England and Northern Ireland, and site bosses are predicting that the planned two-day strike will disrupt supplies for up to a month.
Ineos chief executive Tom Crotty said: 'The union is well aware that a 48-hour strike will cause fuel chaos in Scotland and the North of England for weeks on end.
'This is a huge oil refinery and the union knows you can't just turn it on and off like a tap. A month [of disruption] is our best guess but safety considerations will be at the forefront of everything we do.'
Shortages are likely to result in increased fuel prices, as well as causing widespread disruption for the haulage and farming industries.
'Any blame for the disruption caused by the strike action needs to be laid at Ineos' door,' said Unite union official Linda McCulloch.
'Grangemouth makes up to 3m profit every day. There is no excuse for the company's actions.'
Pressure on Chancellor to cut tax hike
Meanwhile, Chancellor of the Exchequer Alistair Darling is coming under pressure to scrap the 2p-a-litre fuel tax increase planned for October.
The tax rise was previously deferred from March, but now campaigners are urging the Chancellor to scrap the rise altogether, as pump prices hit record highs and analysts predict prices could reach 1.50 a litre by the summer.
Average fuel prices in the UK are currently 108.4p for a litre of unleaded, and 118.0p for a litre of diesel.