Troubled retailer Marks & Spencer is set to tweak its advertising later this year, after unveiling a shock 5.3% fall in like-for-like sales earlier this week.

The company's ad strategy, which has involved using celebrities to promote its ranges of clothing and footwear since 2004, has been widely credited with playing a major role in its resurgence.

However, recent dips in sales may have prompted a rethink.

Asked about the company's advertising, M&S executive director Steven Sharp said: "These campaigns continue to be very successful on the customer measure, but we are looking at some new ideas. I ask you to watch this space."

Sharp added that it was "too soon" to discuss further details, but it is believed that changes to the campaign will be put in place by the autumn.

Meanwhile, pressure is growing on M&S chairman Sir Stuart Rose in the aftermath of this week's sales figures announcement.

One analyst said there was a 40% chance that Sir Stuart, previously hailed as the saviour of M&S, would be forced out if the downturn continued.

The M&S chairman has been criticised for overseeing his own promotion from chief executive to executive chairman, a role which combines the CEO and chairman roles in contravention of City guidelines.