London, UK - Tesco Plc's chief executive, Philip Clarke, who is struggling to turn around Britain's biggest retailer, is facing calls to step down from a top shareholder, the Financial Times reported on Tuesday.

Earlier this month Chief Financial Officer Laurie McIlwee quit the world's third-largest retailer after Wal-Mart Stores Inc and Carrefour.

The Financial Times did not disclose the identity of the top 20 investor calling for Clarke's resignation.

"Clarke has shown he is the wrong person for the job. He has got the strategy wrong," the investor was quoted as saying.

The FT reported that other top shareholders had told the paper that change at the helm of Tesco was inevitable.

A spokesman for Tesco declined to comment on the article.

Having dominated the British high street for years, the 95-year-old Tesco stunned the industry in 2012 when it issued its first profit warning in 20 years and has struggled since then.

In common with Britain's three other leading grocers - Wal-Mart's Asda, Sainsbury's and Morrisons - Tesco is losing market share as it is being squeezed between hard discounters Aldi and Lidl and upmarket grocers Waitrose and Marks & Spencer.

The retailer is almost two years into a turnaround programme under Clarke, but sales are still falling at its 3,150 British stores despite spending on refits, more staff and new product ranges.

It is expected to post another decline in profit when it publishes 2013-14 results on April 16.