Analysts at broker ING have today downgraded their ratings on several of Europe's major retailers, such as Carrefour, Tesco (from buy to sell) and Marks&Spencer (from hold to sell).ING has expressed its caution regarding the sector due to the on-going Eurozone crisis and the associated fiscal austerity measures. In parallel, ING has upgraded Ahold and Morrison to hold from sell, as "defensive alternatives."AB