Carillion has set an annual limit of £15m a year for PFI bid costs amid continuing concerns over the cost of the procurement method.

Speaking at the Public Private Partnerships conference in London, Robin Herzberg, Carillion’s private finance managing director, said he believed that many contractors had set similar limits. He said the average cost of bidding for a PFI education project was £2-3m.

Gordon McKechnie, the head of the Treasury’s PFI unit, insisted that the government was committed to the PFI despite rule changes that put projects on the public sector’s books.