The squeeze on supermarket suppliers started to win greater attention this week as the national press picked up on the plight of supply chain operators.

One Marks & Spencer supplier told The Guardian this week that the retailer had told its suppliers to slash their costs, as sterling’s low rate against the euro and other world currencies takes its toll.

According to other press reports, M&S has attempted to renegotiate terms as its profits have been hit, not just by the fall in value of sterling, but also dampened consumer spending.

M&S has staunchly defended its treatment of suppliers, reportedly saying it is “working hard with them” and is engaged in “ongoing discussions” as usual and treating them with “utmost respect”.

The retailer issued a profits warning in 2008 and this year revealed that Christmas trading was its worst for a decade. Food has reportedly been particularly hard hit.

Fellow top-end grocer Waitrose has also been the subject of supplier grumbles, as the retailer has become more price and promotion focused than usual of late.

And surprisingly this week, Asda’s spot as the cheapest of the UK supermarkets was lost to Sainsbury’s. According to MySupermarket.com, which compares prices across different chains, a basket of 24 everyday items at Asda, including bananas and potatoes, was 5p dearer than at Sainsbury’s this week.