The Bristol-based group said like-for-like sales excluding petrol had grown by 6.4 per cent in the 12 weeks to Easter - well ahead of its larger supermarket rivals - as it seeks to become "Britain's favourite local grocery shop".

Chief executive Paul Mason said the performance was a "solid endorsement" of its local focus as it announced three new stores will open next month in Hove, Bristol and Hopton-on-Sea, Norfolk.

Somerfield has around 900 stores but plans to open around 250 more in the next three years, as well as refurbishing 200 existing stores.

The chain's owners - a consortium including property tycoon Robert Tchenguiz, private equity firm Apax and investment bank Barclays Capital - are looking to sell the business although only one bidder, the Co-op, has reportedly submitted a bid. The consortium is said to be holding out for £2 billion.

Somerfield, which employs 42,000 staff, has already spent £100 million in the past 12 months revamping 250 current outlets.

It expects the 250 new stores planned to add more than £500 million to sales in 2010. All the new stores will be based in high street, city or small town locations to fit with the chain's local focus.

The group - taken private by its current owners in a £1.1 billion deal in December 2005 - made underlying earnings of £227 million on sales of £4.4 billion in the year to last April.

Somerfield began life as JH Mills in Bristol in 1875, but changed its name to Gateway in 1950 because the city was the 'gateway to the West Country'.

It dropped the Gateway name in 1994 to become Somerfield and listed on the stock exchange two years later.

In 1998 the firm bought discount chain KwikSave but sold the brand and most of its stores in 2006 after continued losses despite £130 million of investment. KwikSave went into administration last year.