PizzaExpress, already under pressure from stalkers, released like-for-like sales figures this morning showing turnover at its core business going into a steeper dive.

Sales for the half-year to 29 December were down 4.8% on the same period in 2001, the company said, a decline which had speeded up from 4.4% in the first quarter to 5.1% in the second quarter.

This morning PizzaExpress failed to differentiate between sales at its regional outlets and those inside the M25, which have been hit by declines in customer numbers and an apparent perception that the chain's offer is ageing and lagging behind rivals such as Ask. In October the company said while overall like-for-like sales for the first quarter were down, outside the M25 sales "are showing like-for-like growth." The previous month it had told investors like-for-like sales for the year to 30 June were up 5% year-on-year outside the M25, and down 3% year-on-year inside the M25.

The only silver lining came in sales at its number two chain, Cafe Pasta, where like-for-likes were 5.2% up for the half-year and 2.4% up for the second quarter. However, even this was a sharp slow-down from an 8.5% rise in like-for-likes in the first quarter.

In September PizzaExpress said it would be investing "significant" money to refurbish its poorer-performing older pizza restaurants, many of which were in the London area. Late last year it revealed that it was increasing the size of its pizzas from nine inches to 11. The company is also testing a new concept called Marzano, which offers a wider menu and more stylish design, as part its turnaround strategy.

Today, in a one-paragraph statement, PizzaExpress said the trading environment "remains difficult" and its biggest challenge "continues to be disappointing trading at our core PizzaExpress restaurants, particularly within London". It cited "operational and product initiatives … directed at tackling this situation" without revealing how the refurbishment programme announced in September was going.

The company's troubles have led to a number of potential bidders being seen, while PizzaExpress's chief executive, David Page, is said to have secured backing from PAI Management, a French private equity firm for his proposed management buyout, at a price reported to be between 350p and 375p a share.

PizzaExpress's share price this morning immediately dropped 22p in early trading to 310p before recovering slightly to 320p, still above the 247p it hit late last year but a long way off the 900p-plus seen at the end of 2001