Marks and Spencerâ??s shares fell more than 20 per cent on Wednesday morning after a profits warning from Britiainâ??s biggest clothing chain prompted analysts to slash profit forecasts for the retailer.

Sir Stuart Rose, executive chairman of M&S said that "consumer confidence levels have deteriorated markedly and market conditions become more challenging" since the group reported full-year results in May.

M&S shares, which have fallen nearly 60 per cent in the last year, fell as much as 22.5 per cent in early trading.