Frank Westerman made his comments as negotiations were continuing between Unite and Kent-based engineering specialist Crown House Technology over plans to lay off up to 50 m&e staff.
The company, which is part of major construction contractor Laing O’Rourke, is reviewing its operations following the completion of several major projects, including Heathrow Terminal 5 and the airport’s Arora International Hotel.
Mr Westerman said: “If you look at the workforce they had at Terminal 5, we are talking about the elite of the industry here.
“The staff at Crown House don’t want to leave – it has been a good employer with good pay and conditions and enhanced payments at projects like Arora.”
A Laing O’Rourke spokesman insisted no decisions had been taken over job losses.
He said: “We are discussing how best to reallocate resources as particular major projects are closed out, but no final decision has been taken at this stage.”
Mr Westerman said m&e companies were under pressure: “Everyone is saying they have got good orders books, but the clients are putting jobs back and back.
“A number of major projects have finished and they haven’t been replaced. You could name any major company and they are laying off staff.
“These are highly skilled people being laid off. These are NVQ trained, 30 to 40-year-olds, on high wages of £50,000 a year or more. They are the backbone of the industry.”