London - A two-day walkout by oil workers at the Grangemouth refinery in Britain, which disrupted North Sea oil production, came to an end early Tuesday.

The Unite union, which had called out 1,200 men in protest against changes in the pension scheme at the Scottish plant, warned of further industrial action if the dispute was not resolved.

Ineos, the private company which operates the Grangemouth refinery, north of Edinburgh, said it will be at least a week before the plant is fully operational again.

The strike also closed the Forties oil pipeline, which provides 30 per cent of Britain's daily oil output.

Estimates said the walkout cost the industry 50 million pounds (100 million dollars) a day in lost production.

Late Monday, Britain's Prime Minister Gordon Brown and the leader of the regional government in Scotland, Alex Salmond, discussed ways of resolving the pension disupte at a meeting in London.

Business Secretary John Hutton was due to visit the Grangemouth plant Tuesday and meet industry and trade union officials involved in the dispute. (dpa)