The UK's third-largest supermarket chain, Sainsbury's, continued to lose market share to its rivals over the summer, while Tesco extended its lead at the top.

Market share data based on till receipts was released by research firm TNS this week, providing details of the 12-week period to 14 September.

According to the data, Sainsbury's, which recently lost its position as the UK's second-largest supermarket chain to Wal-Mart's Asda, saw its market share fall to 16.1% over the summer, compared to 17.2% a year earlier.

Sainsbury's failed to make the most of the hot summer weather, which helped lift sales at rivals Tesco and Morrisons, and also had problems with stock availability, reported Reuters.

Meanwhile, market leader Tesco raised its market share to 27.1%, while Asda's market share rose to 16.9% and Morrisons climbed to 6.1%.

Safeway, the chain at the centre of a takeover battle, saw its market share slide to 9.2% from 9.7% a year earlier, amid an uncertain future.