Workers returned to the Grangemouth oil refinery in central Scotland on Tuesday after a 48-hour strike that forced the closure of a major North Sea pipeline system.

UNITE, Britain's largest union, said further industrial action remains possible unless refinery owner Ineos backs down in a dispute over pensions.

Power and steam were restored to the Forties Pipeline, but BP spokesman Richard Grant said it would take several days to safely get it back up to its capacity of 700,000 barrels of crude a day.

Management at the Grangemouth Refinery said it would take two to three weeks to bring the plant up to its full capacity of processing 210,000 barrels of crude per day.

"For safety reasons we say it will take two to three weeks to safely get the plant up and running. The union is saying it will take a week. We will see," said Ineos Group Ltd. spokesman Sion Taylor.

Oil prices fell Tuesday amid expectations that the supply disruption would soon be resolved.

Light, sweet crude for June delivery fell 79 cents Tuesday from the day before to $117.96 a barrel in electronic trading on the New York Mercantile Exchange by midday in Europe.

Business Secretary John Hutton, who was in Scotland on Tuesday, said he was glad the union and the company planned to meet later in the day.

"There is a gap between the two sides that has got to be bridged — only the two parties themselves can reach an agreement. No one can do that for them," Hutton said.

The strike at the refinery led to the closure of the Forties Pipeline System, which brings oil from the North Sea to BP PLC's Kinneil plant. Kinneil is powered from the Grangemouth site.