The statement came as the company, and its parent Seddon Group, were named on a 112-strong list by the Office of Fair Trading regarding an investigation into tender activities in the sector.
Seddon construction director Keith Waddington said cover-pricing was a "common feature" in tendering processes in the UK.
He also described it as a "historic practice".
Mr Waddington added: "We do not believe clients were in anyway disadvantaged by it. The investigation is ongoing… and we will continue to co-operate fully with the enquiry.
"It should also be noted that the OFT says in its statement that nothing has been proved at this stage."