Greenpeace ratcheted up the pressure on multiples to improve fish sourcing policies by "displaying" hundreds of dead fish and crabs at store entrances.

Tesco, Asda and Morrisons in Oxford were targeted in two days of protest this week and similar actions were planned for other stores. Damaged sponges and coral were also on show - a bycatch of beam trawling for Dover sole, plaice and cod.

The group claims Tesco, Morrisons and Asda all continue to sell beam trawled fish, which it would like to see banned from their shelves. Greenpeace has praised supermarkets for improving their seafood policies but said there was still a long way to go to ensure all supermarket seafood is sustainable.

Waitrose and M&S are already getting out of beam trawled fish and Greenpeace said the public's reaction in Oxford had been very positive, with many people signing a petition and talking to store managers.