Just months after its protesters took to the roofs of Asda and Morrisons' stores, Greenpeace is hailing British supermarkets for leading a green seafood revolution - but wants further action.

During Seafood Week next week, campaigners will again be outside supermarkets, with the exception of Waitrose and M&S, talking to shoppers about sustainability in seafood.

In Greenpeace's updated seafood league table, M&S leads the way for a second year running in sourcing sustainable seafood, closely followed by Waitrose.

The report praised Sainsbury's, at number three, for adopting vigorous new measures to stop the sale of some of the most destructively fished species such as skate. Asda, which was bottom of last year's table, is in joint fifth position with Morrisons and Tesco as a result of its commitment to sell only sustainably managed seafood within three to five years.

Somerfield and Iceland came last, but Greenpeace stressed that it appreciated it had been difficult for either of the chains to focus on green issues in the light of corporate upheavals. Greenpeace oceans campaigner Oliver Knowles said: "The seafood industry in the UK is undergoing a revolution, driven by new standards being demanded by supermarkets such as M&S, Waitrose and Sainsbury's."

However, Knowles warned that a large amount of seafood caught by destructive methods is still on sale in supermarkets. "Beam trawling is a destructive and wasteful way to fish for species such as plaice and sole. Up to 70% of what is caught is thrown away.

"Supermarkets should clear their shelves of seafood caught in this way without delay. But in many other ways the supermarkets have made progress.

"Somerfield followed up our earlier campaigning with some delistings and Iceland has a new policy coming out."