Workers voted nine to one against accepting the pay offer, according to union Unite, which includes freezing pay for the first year, followed by 1.5% increase for the second year.

Union bosses warned the country’s low carbon energy sector could be affected if industrial action follows a break-down in talks as thousands of skilled workers down tools.

Bernard McAulay, Unite national officer for construction, said: “This insulting pay offer has been roundly rejected by our members. The employers are hiding behind the economic climate to try and push through this paltry pay offer.”

He added that if the BESA refused to improve its offer, Unite would consider moving towards an industrial action ballot.

“Potential industrial action by skilled workers in the multi-billion pound energy sector could jeopardise the government’s ability to meet its low carbon energy targets,” he warned.

A spokesman for contractors body B&ES, said: “This is very disappointing. The challenges facing most firms in the sector are well known and a promised pay rise in the second year is a positive commitment to the workforce.”