Truck maker Daf, based in Thame, is among several UK commercial vehicle manufacturers being investigated by the Office of Fair Trading (OFT) for suspected price-fixing activity.

As part of the probe, the OFT raided Mercedes-Benz's offices in Tongwell, Milton Keynes, and arrested the managing director of Mercedes-Benz's commercial vehicle wing in Britain, Ian Jones.

Mr Jones, who joined Mercedes in 2002 from Daf Trucks, was later released on bail.

Daf Trucks marketing director Tony Pain said they had received notice of the investigation, but no officers had visited the Thame offices, which employ about 100 people.

Mr Pain said: "We are working with the OFT in response to the investigation of commercial vehicle manufacturers. Until we know more details we are not really in a position to comment." He said DAF would do everything it could to aid the inquiry.

The OFT has also contacted Swedish truckmaker Volvo and its Renault subsidiary, as well as Scania and Man.

A spokesman for the OFT confirmed the investigation of "suspected cartel activity involving commercial vehicle manufacturers in the UK".

She added: "Investigations are being carried out under both the Enterprise Act 2002 and the Competition Act 1998. The investigations are at an early stage. The OFT will not be in a position to conclude whether it considers the law has been infringed until it has completed its investigations and assessed the available evidence."

A spokesman for Mercedes-Benz confirmed the visit took place as part of the OFT's ongoing research: "In that context the OFT carried out an on-site investigation at its offices. Of course, Mercedes-Benz is fully co-operating with the investigation which may take many months or more to complete."

He added that due to the ongoing legal process the company is unable to comment further.