TESCO'S troubles have intensified after new figures for the grocery sector revealed that the supermarket's sales dropped by 4.5 per cent year on year in the 12 weeks to September 14.

The publication yesterday of the figures by Kantar Worldpanel came after the retail chain announced that its new finance director is to start work immediately rather than December 1 as previously planned.

Alan Stewart had resigned from Marks & Spencer in July but his Tesco start date was brought forward after an accounting error revealed that the firm's first-half profit forecast had been overstated by £250 million.

The error, revealed on Monday, deflated the company's profits by millions and, along with the suspension of four senior executives and the company's decision to call in investigators, slashed £2 billion from its stock market worth.

Shares slipped a further 8.5p yesterday to close at 194.5p.

Tesco's chief executive Dave Lewis, who started at the beginning of September, said on Tuesday that M&S chief executive Marc Bolland had agreed to release Mr Stewart early.

Tesco has not had a finance head since Laurie McIlwee officially left the business earlier this month.

M&S confirmed in a regulatory filing yesterday that Mr Stewart's employment as CFO was to terminate the same day.

He had been on gardening leave since July 10, and had held the CFO role at the firm since October 2010.

According to the figures published by consumer research group Kantar, Tesco's market share hit 28.8 per cent per cent, down from 30.2 per cent in the year-ago period. "There is no sign yet of recovery at Tesco," Kantar said.

While Tesco's sales fell to £7 billion, down from £7.4bn a year ago, the discount retailers continued to welcome more buyers.

Aldi's sales for the 12-week period grew by 29.1 per cent, and those of Lidl increased by 17.7 per cent.

Fraser McKevitt, head of retail and consumer insight at Kantar, said: "Consumers are currently benefitting from intense price competition between the grocers."

The publication of Tesco's interim results has been delayed until October 23, from October 1, with analysts predicting further write-offs and negative news on that date.

Analysts at Societe Generale expect a further drop in market share, saying there was a danger now that the accounting issues could delay the setting out of a new strategy from Lewis.

"We think top management and the company as a whole could struggle to wholly focus on day to day business in the coming months and hence expect further deterioration in like-for-like (sales) and market share trends," they said in a note.

Bernstein Research analyst Bruno Monteyne said: "We expect this isn't the end of the bad news."