Tesco has posted its third straight quarterly loss. Reuters

British supermarket giant Tesco has reported falling sales for a third consecutive quarter as it continues to lose market share to its rivals, sending its shares down in early trading.

For the 12 weeks ending 24 May, sales including VAT, but excluding petrol, were down by 3.7% on the same quarter as last year.

"The first quarter has... seen a continuation of the challenging consumer trends in the UK, reflecting still subdued levels of spending in addition to the more structural changes taking place across the retail industry," said embattled CEO Philip Clarke.

On 26 July 2013, Tesco shares stood at 386.40p but after a poor 12 months for what was once the UK's biggest supermarket, they currently stand at 293.45p – the worst they have been since December 2008 – and down by 1.36% on the day of its latest quarterly results.

Clarke has been under intense scrutiny recently after the retailer failed to post a profit since 2012 and investors are beginning to grow weary.

"Clarke has shown he is the wrong person for the job. He has got the strategy wrong," one unnamed major shareholder told the Financial Times in April after the company posted a 6% decline in profits in its annual results.

Commenting on today's numbers Clarke, however, said he expects a recovery from the chain and that Tesco's price cutting will eventually pay off.

"We are pleased by the early response to our accelerated efforts to deliver the most compelling offer for customers," he said. "We expect this acceleration to continue to impact our headline performance throughout the coming quarters and for trading conditions to remain challenging for the UK grocery market as a whole."