U.K. competition watchdog the Office of Fair Trading Wednesday fined six recruitment agencies a total of GBP39.27 million for price-fixing and the collective boycott of another company in supplying job candidates to the construction industry.

Hays Specialist Recruitment, a unit of Hays PLC (HAS.LN), took the bulk of the fine and will pay GBP30.4 million, although the parent company said it is considering an appeal against a sum it considers "wholly disproportionate with the activities to which it relates."

The decision comes just a week after the OFT fined 103 construction firms a total of GBP129.5 million for colluding with rivals on building contracts. That was one of the largest price-fixing probes ever undertaken by the regulator.

The OFT said that it had found that A Warwick Associates, Beresford Blake Thomas, CDI AndersElite, Eden Brown, Fusion People, Hays Specialist Recruitment, Henry Recruitment and Hill McGlynn & Associates had all broken competition rules when supplying candidates to the construction industry. CDI AndersElite is a unit of CDI Corp. (CDI) of the U.S.

It said Beresford Blake Thomas and Hill McGlynn & Associates, both units of Randstad Holding NV (RAND.AE), had been granted immunity from fines because they first provided the OFT with evidence of the cartel activity.

Dutch firm Randstad said its companies had been involved when they were still part of Vedior, which Randstad acquired in 2008.

"Randstad takes all matters of business conduct and ethics very seriously. Our code of conduct, integrity code and competition law guide are implemented throughout the group of companies. In relation to this case clear commitments have been provided to prevent any infringement in the future," it said.

Hays in a statement said it thought the GBP30.4 million fine levied on Hays Specialist Recruitment was too much given the activities to which it relates, Hays' involvement in those activities, and the way the OFT has dealt with other cases in the past.

Hays Chief Executive Alistair Cox said the matter related to a single employee who is no longer with the company and affected only a small part of Hays' construction and property busines. He said the company takes the findings of the OFT probe seriously and had strengthened employee compliance and training in this area.

"At all times Hays has independently determined the price and terms on which it has dealt with its customers and at no stage did the matters investigated by the OFT affect Hays' dealings with its clients," Cox said.

All the companies applied for, and were granted, leniency, apart from A Warwick Associates, which is in liquidation. The leniency meant that the total fine was reduced from GBP173 million.

The company boycotted was Parc UK, which entered the market in 2003 with a new business model to act as an intermediary between construction companies and the recruiters. That put pressure on the recruitment firms' margins, the OFT said, and prompted the companies to set up a forum that boycotted Parc and cooperated to fix the fees they would charge intermediaries and certain construction firms. The OFT said the so-called "Construction Recruitment Forum" met five times between 2004 and 2006.

-By Steve McGrath, Dow Jones Newswires; 44-20-7842-9284; steve.mcgrath@dowjones.com