Robert Wiseman Dairies says Office of Fair Trading (OFT) price-fixing investigators first contacted it three years ago.

The group said it was 'disappointing' the OFT had taken so long to publish last week's preliminary probe findings. Wiseman, which added it would take some time to respond to allegations made against it, also posted a trading update confirming sales and performance were in line with expectations.

The Glasgow-headquartered group was one of five dairy processors to be found provisionally guilty of colluding to increase the price of milk, cheese and butter at a cost of around £270 million to consumers.

Rivals Arla, Dairy Crest, Lactalis McLelland and The Cheese Company were also named in the investigation, alongside supermarket giants Asda, Morrisons, Tesco, Sainsbury and Safeway, now also owned by Morrisons.

The groups could face hefty fines if found guilty.