Waitrose said like-for-like sales rose 9.4% in the 15 week period to May 10.

Total sales at the supermarket were up 5.9%.

Meanwhile, Waitrose said new stores will open at Mill Hill, London on May 29 and Portishead, near Bristol on June 5.

Mill Hill will have a selling area of 18,140 sq ft and Portishead 27,000 sq ft.

Stores at Weybridge, Chichester, Goldsworth Park, Reading and Kingsthorpe will be extended.