The highly successful Happy Egg free range egg brand is facing the prospect of legal action in the United States.
The action is being pursued by the Organic Consumers Association (OCA), which says that the firm has used misleading advertising claims in using the term pasture raised.
The claim has now been lodged in court in the Superior Court of the District of Columbia.
The Happy Egg brand was first introduced by Noble Foods - the UK's biggest egg company - in 2009, and by 2010 it had established itself as the biggest brand in the UK egg category.
It entered the US market in October 2012 when it launched in more than 240 Kroger and Ralph’s stores in California. The eggs are now on sale in stores across the US.
Happy Egg was the first commercial egg producer in the US to be granted humane certification in the American Humane Association’s ‘Layer Hens: Free-Range and Pasture-raised’ category.