Asda has increased first-quarter sales by driving prices down and cutting costs in the supply chain, its parent Wal-Mart said.
Asda's like-for-like sales, excluding petrol, rose 6.4% in the three months to 31 March.
Total sales increased in the "high single digits", Wal-Mart said, driven by an early Easter and the leap day.
"Asda has continued to win in the UK, delivering a strong first quarter, with 30 base points of market share growth despite a challenging economic environment," said Mike Duke, international vice chairman of Wal-Mart.
"Although we expect the UK to remain a challenging economy and retail market over the rest of the year, we believe our strong pricing agenda, backed by a cost reduction programme, leaves us well-positioned to continue to make market share there."