The Swiss-based oil refiner Ineos refused on Tuesday to go to independent arbitration in a dispute with workers at its Grangemouth refinery and petrochemical plant in Scotland, increasing the chances of a full-scale strike.

Ineos and Unite, Britain's largest trade union, have been engaged in a separate war of words about the future of the petrochemical plant.

Last week, Ineos announced a "survival plan" involving job cuts and changes to pension plans to keep the plant in operation.

On Monday, staff across the complex began working to rule and refusing overtime in a dispute over Ineos's treatment of union organizer Stephen Deans.

The union said it could still escalate to a full strike, which would have serious implications for North Sea supply as steam from the plant helps to power the Forties pipeline.

Ineos on Tuesday morning turned down a union offer to take the dispute to the independent conciliation service ACAS.

"We're following due process with the investigation and that's not concluded and, until it is, we don't think there's anything to go to ACAS about," a spokesman for Ineos said.

Separately, Unite said it had agreed to discuss pensions, pay and conditions, and had submitted a transition plan, which Ineos would respond to by Thursday.

"I'm not optimistic, but our offer shows that accusations from the company that we are 'fiddling while Rome burns' are untrue," said Pat Rafferty, regional secretary of Unite.

An Ineos spokesman said Unite had not come up with new proposals but that talks with the union on the future of the plants were continuing.

Ineos says cutting costs is crucial to securing a loan guarantee from the British Treasury of 125 million pounds, and a grant of 9 million pounds from the Scottish government.

It says it is investigating whether Deans' political activities with the Labor Party contravened company policies, and that it will announce its findings on Oct. 25.

The union says both the Labour Party and the police have found no evidence of wrongdoing.

The refinery that the chemical plant is attached to is owned jointly by Ineos and PetroChina.