Marks and Spencer has been dealt a blow ahead of its full-year results tomorrow with news that Tesco has overtaken the retailer in sales of non-food products.

A survey conducted by retail consultancy Verdict Research found that Tesco sold £4.6bn of non-food products in 2004 while M&S sold £4.4bn.

The survey also predicts that the market share of grocers selling non-food products will increase to 12.7% this year with sales of £14.4bn.

Tesco, Sainsbury and Asda are also expected to sell more non-food products than the combined sales of all UK department stores by 2006.

The news is another blow to M&S which has been recently been embroiled in a damaging internal row over the appointment of a chairman.

The appointment of Lord Burns who will take up the position next year ended the row, but investors are now looking to the group to come up with a plan to raise sales which have fallen for the last six quarters.

M&S is also expected to announce the refurbishment of 20 stores at a cost of £300m.