Asda plans to remove North Sea cod from its supermarkets by July because of the massive downturn in natural fish stocks.

In addition, it said it would stop selling swordfish.

The retailer said the decision was partly a response to protests from environmentalists at its sale of endangered fish. It has proposed transforming the North Sea into a marine conservation zone.

It added that it wanted to follow a similar policy to Walmart within five years by only selling fish certified by the Marine Stewardship Council.

Conservationists have welcomed the move.