Sainsbury has been confirmed as the joint top performing food retailer going into 2013, alongside Tesco, following a report by market researcher Kantar Worldpanel.

According to data published Tuesday, both companies delivered a 3.9% cash sales growth rate in the six weeks to January 6th, with market share at the same levels seen a year ago.

For Tesco this compares with four-week growth of 4.2%, indicating that momentum slowed somewhat, while Sainsbury's four-week cash sales grew 3.7%, meaning Tesco is still the frontrunner.

Meanwhile, Morrison's Christmas like-for-like sales dropped 2.5% in the six weeks to December 30th, and cash sales declined 1.0% in the six weeks to January 6th.

The six-week figure for Asda came in at 2.1%, compared to 2.5% for the four-week figure.

Together, the four major grocers delivered growth of 2.7% in the six week period.

Kantar Worldpanel Director Edward Garner said: "This represents a clear improvement in Tesco's fortunes following a series of share dips in 2012, but it is also a strong performance from Sainsbury's which had been predicted to suffer disproportionately from the Tesco fight-back by some commentators."

The ONS food inflation rate was also released Tuesday, revealing that it remained at a relatively high level of 3.6% in December, compared to 3.7% the previous month.

Food inflation is expected by most companies to accelerate in the early stages of 2013.

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