They allege the four conspired to fix the price of chocolate bars between 2002 and 2008 by collectively increasing prices despite a reduced demand for chocolate products.

At the start of 2002 the four chocolate brands, which govern 76 per cent of the US market, claimed increased raw materials costs resulted in the price hike.

But Supervalu has refuted this adding that cocoa prices were stable between 2003 and 2007, sugar remained stable apart from a brief spell in 2005 and milk costs fluctuated within the period.

In documents filed at a Pennsylvanian court, Supervalu has demanded a recompense of three times the amount of damages it sustained and an injunction prohibiting the chocolate manufacturers from any further alleged cartels.