AquaBounty, the Massachusetts company behind the fish, insists it is safe and is hoping for approval within months. Chief executive Ronald Stotish said the fish would be no bigger than normal, simply grown in half the time. He said: "You don't get salmon the size of the Hindenburg. You get to those target weights in a shorter time."

AquaBounty would sell fish eggs to fish farms. They would be bred sterile to prevent them getting into the wild and breeding with native salmon.

But Peter Melchett, policy director of the Soil Association, said: "Once you have bombarded an animal with other genes, the DNA is unstable, and there is no guarantee these fish will remain sterile.

"It poses far too great a risk to wild salmon.