A group of celebrities have written an open letter to restaurant chain Nando’s asking for proof that it is not contributing to pollution in the River Wye.

Actor and river conservationist Jim Murray is one of the group that has signed the letter, which accuses one of the restaurant’s suppliers of dumping waste into the river.

Murray said the restaurant must do more to prove its environmental credentials.

Nandos denies polluting the river and says its direct supplier has said that “no manure is spread, stored or otherwise disposed of” on any of the chicken farms it sources from.