Scotland's biggest chicken producer aims to double its weekly output of free range birds, thanks in part to a campaign by Jamie Oliver and Hugh Fearnley-Whittingstall.

Grampian Country Food Group wants to increase free-range production from 45,000 to 90,000 a week and boost organic output by 5000 birds weekly to 20,000. A spokesman for the firm confirmed the chefs' campaign against battery hens had impacted on the already changing market.

Meanwhile, family-owned Farmlay, near Strichen in Aberdeenshire, wants to add 30,000 dozen eggs to its weekly production because free range sales have risen by up to 30%.

However, sales of standard chickens and eggs have not fallen significantly since the chefs' TV shows in January.