An intense bidding war erupted yesterday between the two heavyweight US consultants as CH2M Hill also revealed it had obtained commitments from shareholders giving it an 18.1% stake in Scott Wilson.

CH2M unveiled the £189m offer for Scott Wilson at 8pm yesterday evening after URS that morning made public a recommended offer of £161m for the UK consulting engineer.

The latest offer represents a 182% premium on the Scott Wilson share price when bid approaches were first declared on 4 June.

A source told the Enquirer: “Scott Wilson shareholders must be rubbing their hands. This latest bid is unlikely to be the final word in what is clearly a battle of wills between two heavyweights for control.”

Scott Wilson has given URS until July 1 to match the offer. URS, which has a matching rights agreement with Scott Wilson, said it was considering its options.

Lee McIntire, CH2M Hill’s chairman said: “While we would have preferred to make this offer on a recommended basis, due to the contractual arrangements that Scott Wilson has with another party, we are making this proposal directly to Scott Wilson’s shareholders.

“We will be seeking a recommendation to this offer from Scott Wilson’s board, and are confident that Scott Wilson’s shareholders will be supportive of what we believe to be a compelling offer.”

McIntire said CH2M Hill had a proven track record of supporting and developing the businesses it bought.

He added that the latest offer was superior to the URS bid both in terms of value and the opportunities it delivered to Scott Wilson, its business, customers and staff.

“We know Scott Wilson and respect the very capable people it has around the world. We believe that CH2M Hill’s model of employee ownership and our shared passion for customer service mean that our offer not only provides shareholders with compelling value but will also provide the business and its employees with the best environment in which to fulfil their full potential,” added McIntire.

The bidding war emerged after Scott Wilson reported full-year results, showing near-doubled, pre-tax profits of £18m, up from to £9.4m in the preceding year, despite revenue slipping to £340.4m from £360m.