Wal-Mart Stores Inc has promoted the chief operating officer of its British supermarket arm Asda to a senior role in its international division.
Judith McKenna will take up the post of executive vice president, strategy and international development at the U.S. firm in April, Asda said on Friday.
Investec analyst Dave McCarthy said McKenna's departure was a loss to Asda, Britain's second-biggest supermarket chain behind Tesco , after she improved in-store standards and kept tight financial control over the business.
"Any weakening of the management team at Asda is good news for the competition. We believe that Asda's competitors will be pleased to see McKenna depart for the US, so bad news for Asda, good news for Morrisons in particular," McCarthy said.
Britain's supermarkets are battling for sales and market share in the face of a weak UK economy, with consumers fretting over job security and a squeeze on incomes.
Asda is not due to report on trading until February but its so-called 'big four' UK rivals have.
On Thursday Tesco posted its highest sales growth in three years over Christmas, while on Wednesday J Sainsbury saw an expected slowdown in sales for its third quarter. Morrisons reported a Christmas sales fall on Monday.
(Reporting by Neil Maidment; Editing by Helen Massy-Beresford)