The UK market leader, which has operations in 14 countries, saw its shares slump by 55.1p, or 14%, to 329.4p while Morrisons tumbled by 7% and Sainsbury's fell 5%. But, boosted by a rapid store opening programme, Tesco's total UK sales, excluding petrol, rose by 1.7%. The world's third-largest retailer grew group sales by 4%, driven by strong international revenues, particularly in Asia and the US.