Is Jamie heading for the checkout?

He has been the face of Sainsbury's for five years.

But Jamie Oliver could find himself back on the shelf after the troubled supermarket decided to change its advertising format.

To cut costs, the firm is reviewing its £45million-a-year account with the agency which makes the adverts featuring the celebrity chef.

Separately, 29- year- old Oliver's own contract with Sainsbury's, from which he earns nearly £1.2million a year, is up for renewal in May.

Sainsbury's, Britain's most successful supermarket ten years ago, is now behind Tesco and Asda - although some analysts believe things would be even worse without the Naked Chef ' s cheery personality endorsing its products.

The firm revealed its first loss in 135 years of trading in November after a £3billion spend on computer systems failed to keep the shelves stocked.

It has used advertising company Abbot Mead Vickers for 25 years, but says it wants new adverts to focus on getting the message across that it has 'great food at fair prices'.

One suggestion is that Oliver will be dropped from advertisements but kept on as a 'food consultant'. A Sainsbury's spokesman said annual discussions over Oliver's contract had begun, 'but at the moment it's business as usual'.

A spokesman for Oliver said: 'Jamie negotiates his contract every year. There is nothing unusual in the fact that they have put the advertising out to tender and it is completely separate from anything to do with Jamie's contract.'