Organic chicken is fattier and less nutritious than standard chicken, new research claims.

The University of Strathclyde's scientists said tests on supermarket-bought chicken breasts showed organic ones contained fewer Omega-3 fatty acids and lower antioxidant levels that affect the taste, despite the price tag on an organic bird, which is two times higher than conventional chicken.

Shoppers may be better off buying free-range or broiler chickens, said Alistair Paterson, author of the study. "There's no guarantee that chicken gives you more Omega-3, better taste or a lower cholesterol level."

The Soil Association has angrily dismissed the report as bad science. A spokesman said the study was based on two organic chicken breasts compared with seven conventional and free-range ones.

"You've got to take the conclusions with a pinch of salt. It is unscientific to suggest that any data based on the analysis of two samples, the source and age of which are unidentified, can provide valid information about the nutritional content of organic and non-organic chickens."

Other studies by the University of Perugia, Italy and the London Metropolitan University came to a different conclusion. They claim organic chicken contains more Omega-3 and has better muscle development than its battery equivalent.

The poultry industry wasn't ruffled over the study, either. "It's probably quite true," said Peter Bradnock, chief executive of the British Poultry Council.

"It's just a matter of taste. The point is, all poultry is very good for you and high in nutrients."

Organic chicken accounts for less than 1% of total annual sales - less than £20m a year. Free-range sales account for some 5.5% of sales, with the rest in conventional broilers.