Twenty-two construction companies raided amid suspicions of collusion in assembling tenders.

The Office of Fair Trading has swooped on the premises of 22 companies in the East Midlands as part of a continuing crackdown on cartels in the construction industry.

OFT officials have raided firms in Nottinghamshire, Leicestershire, Derbyshire and South Yorkshire amid suspicions that they had been colluding in assembling tenders over the past five years.

No details had been released of the firms’ identities, or even the sectors they cover, as Building went to press.

A spokesperson for the OFT said a decision on whether to prosecute the firms had yet to be made.

The spokesperson said: “We had reasonable grounds to suspect a breach of the Competition Act, but we haven’t actually come to any conclusions yet. Construction is one of our priority areas.”

In a statement, the OFT said the investigation could uncover behaviour in breach of the criminal cartel offence under section 188 of the Enterprise Act 2002.

However, it added: “At this stage no assumption should be made that because the OFT has conducted a search of a company’s premises that a company or any of its employees have breached competition law. The OFT will carefully consider the evidence it has obtained before deciding whether any such breaches have occurred.”

The OFT has already conducted investigations into roofing contractors in the North-east and the West Midlands. It operates a leniency policy under which companies that report anti-competitive behaviour may qualify for 100% immunity or significant reductions in financial penalties.

The latest raid comes two months after Building revealed that a company that disclosed vital information to the OFT about illicit cartels in the roofing industry had received a blackmail threat.

Roofer Briggs Roofing & Cladding went to the OFT after an individual threatened that he would disclose information to the authorities unless he was paid off.