LONDON (AP) — British contract workers walked off their jobs at British energy facilities Friday, part of an escalating dispute triggered by the employment of foreign workers.

Tensions flared after French oil and gas company Total fired more than 600 contract workers Thursday for participating in a wildcat strike at its Lindsey Oil Refinery in northern England. The strikes have spread to other power stations, including Drax, the nation's largest coal-fired plant.

Lindsey, the nation's third-largest refinery, was the subject of a wildcat strike earlier this year when Italian construction company IREM SpA imported Italian and Portuguese labor to carry out major expansion work. The dispute was resolved in February, but it flared again last week after Total dismissed 51 workers. About 1,200 contractors walked out, claiming the company had reneged on an agreement not to lay off any workers.

Total responded by firing 647 contract workers and said they had until Monday to reapply for their jobs. Proposed talks between the union and management, due to be held Friday, fell through.

Bernard McAulay, an official with the UNITE union, told a crowd of picketers at the parking lot across the Lindsey refinery, about 165 miles (265 kilometers) north of London, that while foreign workers had their place, "the first priority has got to be labor from the local community."

"These companies have a social and economic responsibility to the people of the community," he said.

Under EU rules, laborers from inside the 27-nation bloc have the same right to work in Britain as British citizens — just as Britons have the right to work in other EU nations. But the issue is becoming a sensitive one as Britain's economy weakens.

Workers at about a dozen other plants and refineries have walked out in solidarity with those laid off at Lindsey. British Energy's Hinckley Point B nuclear power station in southern England was affected by a walkout, as was npower's coal-fired Aberthaw plant in Wales, where management reported that 300 contractors left their jobs.

The walkouts have yet to affect electricity generation.

Unions such as UNITE, the nation's largest, have condemned Total but have shied away from officially endorsing the workers' action. Such a move would be illegal, according to Cambridge University law professor Catherine Barnard, because under British law strikes must be endorsed by a formal vote.

If "unions don't comply with notice and balloting procedures, they can be sued," Barnard said.

The BBC said those picketing outside the refinery held signs saying "Put British Workers First." Britain's Press Association news agency quoted one unnamed striker as saying that laid-off workers feared they would be replaced with low-paid foreigners.

Prime Minister Gordon Brown, who in principle endorsed the idea of "British jobs for British workers" in a 2007 speech, has come down against the strikers, saying through a spokesman unofficial strikes were "never the right response to industrial relations."

Barnard said the government might be pushed to intervene if it feared the dispute could be capitalized on by right-wing extremists.

Workers from Eastern Europe flooded into Britain after the Czech Republic, Hungary and Poland joined the European Union. Even in boom times, the flow of immigrant labor raised hackles in some quarters. With a recession pushing Britain unemployment rate to 7.2 percent, according to the most recent figures available, experts fear more anti-immigrant hostility.