UPDATE 1-Asda's sales slump as big UK supermarkets struggle

(Adds table, details)

LONDON, May 4 (Reuters) - Sales at Wal-Mart's

British supermarket chain Asda fell 5.1 percent in the

12 weeks to April 24, the worst performance in a period when all

four of the country's big chains saw sales declines, industry

data showed on Wednesday.

Market researcher Kantar Worldpanel said sales at market

leader Tesco fell 1.3 percent, ending four months of

improvement, while Sainsbury's and Morrisons

saw falls of 0.4 percent and 2.6 percent respectively.

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