Asda, Britain's second-biggest supermarket group, posted a 5.5 per cent rise in second-quarter like-for-like sales excluding fuel and said it was taking market share at the fastest rate for a number of years.

The firm, owned by US retail goliath Wal-Mart Stores Inc., said underlying sales, adjusted for the timing of Easter, rose six per cent in the three months to June 30, up from five per cent in the first quarter.

Asda, which is focused on the budget end of the grocery market, said its market share rose 0.6 percentage points to 12.3 per cent in the 12 weeks to July 13 on the same period last year.

"Asda is gaining market share at the fastest rate in many years," chief financial officer Judith McKenna said in a statement.

"In addition, Asda surpassed its plans for both sales and operating income, in spite of a slowing economy." The firm, which competes with market leader Tesco, J Sainsbury and Wm Morrison, said sales of both its budget Smartprice and upmarket Extra Special ranges rose more than 20 per cent in the quarter.

Wal-Mart, the world's largest retailer, operates about 6,000 stores worldwide including more than 3,000 stores in 13 countries outside the US and it is starting to shift more investment away from its saturated home base.

Separately, Wal-Mart reported a 17 per cent rise in second-quarter profit and raised its full-year earnings view. Wal-Mart's expansion push is rivalled by global competitors, France's Carrefour and Tesco, both of which are also seeking access to emerging market consumers to offset slowing growth at home.