Balfour Beatty has slashed its back office workforce as part of its move to reduce costs by £100m.
Up to 400 staff have been made redundant in the first half of the year, with the job cuts concentrated on functions such as IT, finance and legal.
Chief executive Leo Quinn said: “There’s clearly been a headcount reduction of 300 to 400 people.
“Department budgets have effectively been halved; you can’t do that overnight, [but] we’re trending down in all our expenditure.”
Mr Quinn said £25m had already been taken out of the group’s cost base, adding that the savings made so far were “low-hanging fruit”.
He highlighted the company’s previous £120m IT budget, calling it a “crazy, ludicrous amount of money”.
However, he said the headcount in the firm’s customer-facing functions would not be reduced.
“We are really focused on maintaining frontline capability,” Mr Quinn confirmed.
“We are not looking at losing any people that are customer facing.”
The news of the job cuts came as Balfour Beatty yesterday revealed it had made a £150m loss in the first six months of 2015, with loss-making legacy construction contracts blamed for keeping the company in the red.
Earlier this year, Mr Quinn had said there would be “no wholesale redundancy programme” at the firm.