A major British oil refinery moved closer to permanent closure on Monday after a clear majority of union workers rejected a pensions and benefits offer from the Swiss-based operator Ineos.

At least 665 of 1,023 union members at Grangemouth, Scotland's only refinery, rejected the offer, the Unite union said.

Ineos management will meet on Tuesday morning to discuss the vote, and a decision on the future of the plant will be made shortly after that, Ineos spokesman Tom Crotty said.

"It will take as long as it needs but we'll not sit around for days, the refinery is losing around 2 million pounds per day, so we need to resolve it," he said.

The 210,000 barrels per day from Grangemouth oil and petrochemicals plant supplies most of the fuel for Scotland and powers BP's BP.L Kinneil oil terminal, which processes North Sea crude coming ashore via the Forties Pipeline System.

Problems at Kinneil have in the past helped push world oil prices higher.

The union said that the solid rejection by its members should force the company to change tack and negotiate, rather than dictate new terms and conditions.

"The people of Grangemouth and Scotland will be expecting Jim Ratcliffe (Ineos Group's chairman) and the Ineos shareholders to now take heed.

"Do the right thing tomorrow, drop the threats to the workforce, fire up the plant and get around the table at (arbitration service) ACAS," said Pat Rafferty, Scottish secretary of Unite, Britain's largest union.

Ineos said last week it had closed the refinery and petrochemicals complex pending an outcome to the dispute.

PetroChina owns half of the refinery, which Ineos operates. Ineos owns 100 percent of the attached petrochemical plant.

Local MP Michael Connarty, said: "I don't think they're looking to close the refinery, but if they shut the refinery it would be a death blow to a lot of the Scottish economy."

Scotland's first minister Alex Salmond, leading a campaign to secure his country's independence in a referendum next year, said he had held extensive talks with Ineos and Unite looking for common ground.

Ineos' Crotty said that the plant could be fully up and running within two weeks of any agreement.