Marks & Spencer has registered a surprise improvement in sales at its clothing division - the first rise in more than three years of trading.

The 0.7% lift in like-for-like sales in the general merchandise arm came as customers responded to changes in "product quality and styling" and as it sold more full-price items.

The company's food business also saw like-for-like sales in the 13 weeks to March 28 rise by 0.7%, helped by record Valentine's sales.

Shares opened 4% higher after the company's fourth quarter sales figures beat City expectations.

The group said its spring and summer collections have been well received, but its progress in clothing was partly disrupted by more stock going into the Christmas sale as a result of the unseasonal conditions through the autumn and winter season.

Analysts had expected the retailer's general merchandise unit to report a 1.2% fall in like-for-like sales.

The firm also said that its online sales returned to growth of 13.8%, with its traffic numbers and customer satisfaction ratings continuing to improve since distribution problems impacted Christmas trading.

The retailer said the specialist positioning of its food business continued to deliver results in a deflationary market, caused by ongoing supermarket price wars. The business said it introduced over 350 new products during the period.

Chief executive Marc Bolland has been under increasing pressure to turn around the clothing business, which until today had experienced sales declines for 14 quarters in a row.

The retailer's performance has stuttered despite turnaround efforts including a multi-billion pound investment drive, the hiring of new fashion executives and a celebrity-driven marketing push.

Mr Bolland said: "We have made strong progress over the quarter. In food we delivered another excellent performance, with sales growth ahead of the market.

"We continued to deliver on general merchandise gross margin, and are pleased that we have achieved this whilst also improving general merchandise sales."