Food retailers are getting crushed this morning

It's not been a great morning for the supermarkets.

Morrisons, the third biggest grocer on the FTSE 100, is leading the index lower after an shock Christmas update - like-for-like sales were down 5.6 per cent. Shares have fallen over five per cent to 240p.

Meanwhile, Tesco saw sales decline 2.4 per cent over the festive period - a markedly worse result than analysts had been expecting. Its shares are currently down over three per cent.

Yesterday Sainsbury's posted a sharp slowdown in sales over the Christmas quarter, with chief executive Justin King labelling discount rivals an "all-year" threat.

It's a different story, however, for supermarkets sitting either end of the spectrum, with Waitrose reporting a strong performance over Christmas yesterday, and discounters Aldi and Lidl predicted good results.