Ethical Consumer magazine has called for a boycott on tuna sandwiches from Tesco, Boots, Greggs and Subway.

This is on the grounds that the methods used to catch the skipjack tuna used in the products results in the unnecessary deaths of thousands of sharks, endangered Green Sea Turtles and other marine wildlife.

The magazine’s publishers say that of the top five sandwich retailers only Marks and Spencer currently use tuna caught by pole and line, which doesn’t kill other species.