(Reuters) - Wal-Mart has turned to the chief of its Chinese business Sean Clarke to revive Asda, its British supermarket group which has been the biggest casualty in an industry price war that has hammered its sales for nearly two years.

The U.S. group said Clarke would take over from his namesake Andy Clarke at Asda on July 11, tasked with repositioning the chain, which ranks third after Tesco and Sainsbury's, in the "very competitive" British marketplace.

The move comes as a surprise after Andy Clarke said last week that Roger Burnley would succeed him at some point after the incoming executive joins the firm in October. Asda poached Burnley from rival Sainsbury's last year.

Wal-Mart International's president and chief executive David Cheesewright said Burnley would be deputy chief executive, and he viewed him as a "top talent and future chief executive".

Sean Clarke, who started his career at Asda in 2001, said he was "looking forward to returning to the business that got him hooked on retail".

He rejoins a supermarket that has reported seven straight quarters of underlying sales declines, and a loss of market share, including surrendering its second place in the market to Sainsbury's, according to industry data.

Asda has been the laggard among Britain's big four supermarkets, which also includes Morrisons, as German discount chains Aldi and Lidl have successfully targeted British shoppers.

Andy Clarke has run Asda for six years.

Wal-Mart said last month it would shift the balance of Asda's strategy from protecting profits to protecting market share, indicating more price cuts might be on the way.

The company also said Dirk Van De Berghe, CEO of Wal-Mart Canada, will take over leadership of Walmart's China business.

(Reporting by Parikshit Mishra in Bengaluru and Paul Sandle in London; Editing by Sunil Nair and Kate Holton)