Hain Celestial, the US-based organics group, has defended its use of certain fatty acids in its Earth's Best infant formula.

Hain, along with companies including US dairy giant Dean Foods, is at the centre of claims that the ingredients cause diarrhoea and vomiting in infants.

US pressure group The Cornucopia Institute has claimed the "toxic solvents" - hexane-extracted omega-3 and omega-6 fatty acids, or DHA and ARA, derived from algae and soil fungus - cause the illnesses.

The institute has filed a legal complaint with the US Department of Agriculture (USDA) to urge the agency to "enforce the organic regulations prohibiting toxic solvents from being used in the production of organic food".

The lobby group cited products, including Hain's Earth's Best infant formula and Dean Foods' Horizon Organic milk with DHA, as containing the supplements.

However, Hain told just-food that the USDA has approved the use of DHA and ARA under regulations that allow the addition of nutrients to organic products.

The institute's petition to the USDA follows its publication in January of a report that questioned the safety of DHA and ARA in infant formula products.

Martek Biosciences, the company which supplies the supplements to Hain for the Earth's Best product, then labelled the report as "false and sensationalist".