Both were among ten firms fined nearly £60m by the CMA with Keltbray hit with a £16m fine and Squibb a £2m penalty.

Keltbray said: “Keltbray strongly condemns anti-competitive practices and fully cooperated with the regulator’s enquiries throughout the investigation and agreed to settle.

“As today’s release by the CMA has highlighted, Keltbray did not instigate any infringement activity or benefit financially from the infringements, and therefore believes the intended penalty is excessive when compared to Keltbray’s level of involvement, particularly when compared to the malpractices of other organisations who did benefit financially from their activities.

“Keltbray is therefore disappointed with the level of penalty which the CMA intends to impose on it and will be appealing that decision.”

Darren James, Chief Executive Officer said: “The reported CMA penalty is based on Keltbray’s total group turnover, rather than the actual level of culpability relevant to the wound down subsidiary. Keltbray is a large, highly diversified business, with demolition representing a small proportion of total revenues. Keltbray will be appealing today’s penalty decision.”

Squibb Group said it is in discussions with its lawyers about a possible appeal.

It said: “It is disappointing that after four years of investigation, which included reviewing over 10,000 Company tenders and extensive representations by the Company, where we fully cooperated with the CMA (including a root and branch review of our historical compliance practices) that it has been determined that Squibb Group Limited has committed two acts of simple cover pricing.

“In relation to the allegations of cover pricing it is also our understanding that the clients were not disadvantaged, and these two instances are considered to be at the low end of the scale of seriousness in terms of overall economic effect.

“Furthermore, we believe that the proposed fine (which is significantly influenced by a company’s turnover) is disproportionate when seen in the context of the wider investigation and the other infringements discovered as part of the CMA investigation.”