Germany's national competition regulator confirmed on Friday it was investigating illegal price fixing at nine production and distribution plants. A further five have been issued with written notices and the home of one suspect has been searched.
The Süddeutsche Zeitung newspaper reports that between 80 and 90 percent of major plants processing both potatoes and onions had been regularly fixing prices with supermarket chains.
The result, according to the paper, has been a rapid hike in profits, mostly at the expense of consumers who paid inflated prices.
But farmers purchasing seed potatoes are also thought to have been victim of what the German media have dubbed a Kartoffel Kartell (Potato Cartel)
One insider told the Süddeutsche Zeitung that certain ringleaders would call representatives at discount supermarket chains before the weekly order was made to confirm prices, which generally differed by no more than a few cents week-on-week.
But the manager of one of the firms accused of price fixing has rejected the allegations. “We don't have a guilty conscience,” he told the paper.