A rash of unofficial strike action and protests broke out Thursday across the U.K.'s energy plants as workers voice their support for contractors at Total SA's (TOT) 200,0000 barrels-a-day Lindsey oil refinery in Lincolnshire.

The dispute at Lindsey started a week ago, after Total wrote to 65 workers to tell them the hydro-desulfurization project they are working on was close to completion, putting their jobs in doubt.

This is the third episode of rapid industrial action to hit the U.K.'s energy industry in the last five months, but far from paralyzing production the action has so far failed to affect output from the plants, according to the companies that manage the installations. The speed of the action has been attributed to increased use of mobile technology and social networking sites to mobilize workers.

The first period of unofficial strikes took place in February following a dispute at Lindsey over use of foreign workers, culminating in an estimated 2,000 workers out at more than a dozen other refineries, power plants and energy facilities across the U.K.

The second followed in May after a dispute between contractors and industrial services company Hertel at Dragon Liquefied Natural Gas terminal in Wales, which triggered walkouts by hundreds of contract workers at several sites. The action forced Hertel to withdraw 40 non-U.K.workers from a project.

While there has been little if any impact to output at these sites the contractors hired by the energy companies have been forced in to making concessions, sparking government debate over how the U.K. can manage calls from workers and companies for protection from foreign competition.

Earlier Thursday workers at BP PLC's (BP) Saltend Chemical Plant near Hull downed tools to join protesters at Scottish and Southern Energy PLC's (SSE.LN) Fiddlers Ferry power plant in Cheshire, northwest England.

There has been similar action on a wider scale at Drax Group PLC's (DRX.LN) coal-fired power generator in Yorkshire, northern England and at Ratcliffe power station in Nottinghamshire, central England, which is owned by E.ON U.K., a subsidiary of E.ON AG (EOAN.XE).

"I can confirm that some contractors have not come in to work today, in support of fellow workers at another site," said Drax Power spokeswoman Melanie Wedgbury. "We believe those people number less than 200." Wedgbury said daily production at the plant hadn't been affected as the contractors were working on construction projects.

-By Angela Henshall, Dow Jones Newswires; +44 (0)20 7842 9285; angela.henshall@dowjones.com