Hundreds of people staged a demonstration today at the site of a new power station to complain that workers were being hired from overseas, denying jobs to UK employees.
Unite and the GMB claimed vacancies for welders, steelworkers and other construction roles at the Staythorpe site in Newark, Nottinghamshire were being filled by Spanish and Polish workers.
The unions said the decision by contractors building the plant was a "national scandal" and warned that protests could spread to other power stations under construction.
Unite claimed none of the 850 jobs involved in the building of the Staythorpe power station was being earmarked for UK workers.
Steve Syson, a regional Unite officer, said more than 400 people took part in today's protest despite appalling weather conditions.
"The Government is trying to kick start the economy and create new construction jobs, but we have serious concerns that many of these jobs will go to non-UK labour.
"There are similar problems at other power station sites."
Derek Simpson, joint leader of Unite, said: "Staythorpe is a national scandal. We are seeing thousands of jobs being lost daily but at Staythorpe there is skilled, well-paid work available. It's a disgrace that local workers with years of experience are being locked out of the job."
Mr Simpson said engineering giant Alstom, which is building the site for power giant RWE, had the power to insist that the sub-contractors end the "scandalous" situation.
"UK workers must be given a fair chance to get a cut of the action to build a new generation of UK power stations. They are not asking for special favours, they are demanding fair play.
"It will be a disgrace if UK workers are shut out from building their own power stations. Unite will not stand by and allow our members to languish on the dole while there is work in the UK."
Keith Hazlewood, national officer of the GMB, added: "GMB met with Alstom and received assurances they that they would instruct the four sub-contractors to obey the law and not discriminate against the employment of UK labour at both sites and that they would do the same.
"These assurances have not been honoured. Unions were told that Alstom itself will employ 250 Polish workers from the end of January on top of the 50 Spanish workers already working there for the sub-contractors."Reuse content