TESCO has said it will launch a line of indoor-bred slower-grown birds next year.

The supermarket said that the new line would meet all points in the Better Chicken Commitment, including using slower-grown breeds of bird stocked below 30kg/ sq m.

Windows will also be required in sheds, as will enrichments such as bales and perches.

But Tesco will continue to sell Red Tractor chicken, as well as free range and organic.

A spokesman for the supermarket said it was still “working through the details”, but claimed the product would be “affordable” when compared to standard Red Tractor birds.

This new line will mark the first higher-welfare indoor-bred bird that the supermarket has stocked.

A statement said: “All our fresh chicken meets or exceeds Government-approved industry welfare standards, as well as Red Tractor. Our Organic and Finest brands meet the Better Chicken Commitment and early next year we’ll be extending our range of higher welfare chicken which will also meet this commitment.

“Working with our farmers and suppliers, we are committed to continuously improving the quality of our range to stay in line with best practice and animal welfare expertise.”

The RSPCA said it was disappointed the supermarket was not switching its entire supply chain to the Better Chicken Commitment.

“While it’s encouraging to hear that Tesco is looking to introduce a higher welfare indoor reared range of chicken it is extremely disappointing that the supermarket will not fully commit itself to moving all of its standard chicken to meet the requirements of the commitment by 2026.”

Last week animal rights group Open Cages sent a letter to Tesco chief executive Dave Lewis calling for the supermarket to join the comittment. It was signed by 25 specialists including TV’s Chris Packham and former deputy chief vet Alick Simmons.