Animal welfare concerns need to be fully allayed before Freedom Food follows the egg industry's lead in doubling the maximum number of free-range hens allowed on British farms, the RSPCA has said.

The British Egg Industry Council has amended the Lion code of practice to allow maximum stocking densities to be increased from 1,000 birds/hectare to 2,000, effective from January. The switch halves the amount of space per bird from 10 sq m to five.

BEIC said it made the switch in order to give British producers more opportunity to meet the growing demand for free-range eggs, and chief executive Mark Williams stressed the change meant UK stocking densities were still well below the EU limit of 2,500 birds/hectare. UK producers would retain a difference over their EU competitors, while birds would still have a large roaming area, he added.

The RSPCA said it was still considering whether to alter Freedom Food standards in line with Lion, stressing it was evaluating whether such moves would be detrimental to animal welfare. Freedom Food currently allows 1,000 hens/ha over the life of the flock, although maximum densities of 2,500/ha at any one time are allowed.

The organisation is canvassing opinion from producers, scientists and vets, as well as visiting EU farms with stocking densities of over 1,000 hens on the range to assess the animal welfare impact, while the University of Bristol is in the first year of a three-year RSPCA-funded study into range enhancement.

"The RSPCA has had very positive dialogue with the industry and would gladly consider further evidence," said senior scientific officer Alice Clark. "We are not ruling out the possibility of increasing density, but need to be convinced it can be achieved without compromising welfare."

British Free Range Egg Producers Association chairman Tom Vesey said the BEIC move would make planning consent easier and allow more smaller farms to expand.