They included 700 workers at the Grangemouth refinery in Scotland, run by Ineos Group, 400 workers and supporters at a refinery in Wilton in northern England, 100 at a gas terminal near Peterhead, northeast Scotland, and 50 people at the Aberthaw power plant in Wales.

'Right to work'

Unions say Total has excluded Britons from its building contract, bringing in workers from abroad instead.

They believe the move flies in the face of promises made by Gordon Brown, the British prime minister, to provide "British jobs for British workers".

Shona McIsaac, a local Labour politician, said the decision to hire foreign contractors was "like a red rag to a bull for people in our community who are out of work".

Bernard McAuley, of the Unite trade union, told protestors at Lindsey: "There is sufficient unemployed skilled labour wanting the right to work on that site and they are demanding the right to work on that site.

"We want fairness. We want the rights of our members to have the opportunity to be employed, not just on this job but on all jobs around the United Kingdom."

Total has said protests at the refinery, which can process 200,000 barrels of crude oil a day, have not affected production, and that the new contract would not result in any redundancies among existing workers.

Britain is facing rising unemployment, with the rate currently at 6.1 per cent.