Marks & Spencer reported its worst quarterly sales performance for two and half years this morning, prompting its share price to plunge by nearly 20%.

Shares in the department store chain fell 95p to 408.5p after it reported a drop in like-for-like sales of -2.2% for the 13 weeks to 29 December. Of that figure, sales of M&S’ non-food items fell by 3.2% and its food items fell by 1.5%.

The slump by M&S, one of a number of retailers experiencing a fall in share price, brings to an end nine consecutive periods of growth for the company.

In a statement to shareholders, chief executive Stuart Rose remained optimistic about the year ahead but acknowledged it would be a tough trading environment.

He said: ‘We expect trading to remain tough throughout 2008. We are well positioned with a strong offer and better than ever values across our business. We now have 70% of our stores in the modernised format and a strong pipeline of new space for 2008 and beyond.’