Sales were driven by more shoppers looking for lower prices and value for money, the retail giant said without revealing sales figures.
Asda had benefited from the good weather at the beginning of the month with strong sales of fresh foods, seasonal products and George clothing, said Mike Duke, vice chairman of Wal-Mart International.
“Recent independent market share data has confirmed a growing position for Asda in food, clothing and general merchandise,” he added.
Sales in Wal-Mart's international division for the four weeks ending 30 May rose 9.8% to $31.04bn (£15.9bn). Sales were strongest in the UK, Brazil and China.