Oil was being delivered to Scotland from mainland Europe as some 1,200 employees started a 48-hour strike at Grangemouth refinery Sunday after talks on better pension provision failed, the dpa reported.
To avoid bottlenecks in oil supply to Scotland, 65,000 tons of fuel was being imported from mainland Europe, Business Minister John Hutton said at the weekend.
Pat Rafferty of the trade union Unite told Britain's BBC news network that union members were angry and disappointed at the failure of the talks.
Production had already halted at the only refinery in Scotland before the strike started.
Gordon Grant of the refinery's management team said the union had not given the talks enough time. He said it was a sad day for the refinery.
Energy company BP had already closed the North Sea Forties pipeline, through which a third of Britain's crude supply flows, ahead of the strike.
Chemical company Ineos refines 210,000 barrels of oil a day at the Grangemouth refinery. One barrel of oil contains 159 litres.
Experts estimate the shut-down will cost some 50 million pounds (100 million dollars) per day.
The British and Scottish governments have warned of panic-buying at petrol pumps.
There was enough petrol to last through the strike as long as car drivers did not change their habits and buy more petrol than normal, Hutton said.
There were reports of long queues and rationing at Scottish petrol stations.
Ineos said it would take two to three weeks after the strike ends for the refinery to return to normal.