The New Economics Foundation, a think-tank with links to the Treasury, has proposed that Tesco should be broken up, arguing that the huge scale of the UK's biggest retailer is damaging communities and local enterprise.

The call reflects disquiet at the size of the supermarket chain among left-leaning policy bodies, community groups and among small business organisations. It is an echo of a much noisier debate in the US about the dominance of Wal-Mart.