Carillion has been granted leniency in return for helping the Office of Fair Trading with its inquiry into the industry.
A statement from the firm confirmed that it had been working with the OFT since the competition watchdog raided offices of its newly acquired Mowlem subsidiary in 2006.
The statement said: "Carillion notes the announcement today by the OFT concerning its Statement of Objections relating to tender activities in the construction sector, in which it names one of its subsidiaries, Carillion JM Ltd, formerly Mowlem Limited. The Statement of Objections does not involve any other business within the Carillion group, including the recently acquired Alfred McAlpine operations.
"Carillion announced in March 2006 that the OFT had visited two Mowlem offices, shortly after the acquisition of Mowlem on 12 February 2006, and that it would fully co-operate with the OFT's investigation. The OFT's enquiries related to certain matters that arose prior to Carillion's acquisition of that business.
"Subject to ongoing cooperation, the OFT has granted leniency to Carillion JM Limited, thus reducing any fine which might ultimately be levied.
"Immediately following the acquisition of Mowlem, Carillion took steps to apply its own procedures and to ensure compliance within that business of the requirements of the Competition Act 1998, to which Carillion attaches the highest importance.
"Carillion will continue to cooperate with the OFT and respond to its Statement of Objections in due course."