Marks & Spencer revealed strong sales of food over the important Christmas trading period but clothing sales fell back as it continues to battle the after-effects of last year’s crippling cyber-attack.

Stuart Machin, the chief executive of the high street stalwart, said its clothing, homeware and beauty business was also affected by “fragile consumer confidence and milder weather”.

In November, M&S revealed that underlying profits had more than halved to £184.1m in the six months to 27 September, from £413.1m a year before, after it had to halt online orders for more than six weeks because of the cyber breach.

Machin said the poor Christmas fashion sales were linked to “the long tail impact on stock data and management following the incident” as well as “reduced high street footfall”.

The numbers add to fears that fashion retailers have experienced a tough autumn and winter amid mild weather and a squeeze on household budgets caused by high energy and food bills.

M&S is also thought to have lost out to rival Next which recorded bumper sales over Christmas partly thanks to its slick online service.

Machin said the business would “accelerate the reshaping strategy” – under which it has been closing and moving stores that contain clothing and adding more space for food – “against the context of an uncertain consumer environment”.

M&S now has about 230 full-line stores, which contain clothing and food, and almost 800 food-only stores.

The retailer said sales at established stores rose by 5.6% in the three months to 27 December while clothing sales fell 2.9%. Total sales rose by 3.3% to £4.15bn, excluding the addition of its Ocado joint venture the numbers for which M&S has begun to report.

Machin said M&S’s non-food business was “getting back on track as we work through the tail end of recovery”.

He said the food business had gained market share with sales growth underpinned by strong sales of core grocery items with new products and upgrades on products such as Italian ready meals, in-store bakery an deli all bringing in more shoppers.

Sales at its online grocery specialist Ocado increased by 13.7% as the number of items ordered jumped by 10.7 % and the number of orders increased by 11%.