Marks & Spencer has said it expects to make a full recovery after a cyber-attack paralysed its online clothing and home operations, leading to adjusted pre-tax profit for the retailer to plummet more than 55%.

The disruption, which occurred in April, wiped out a massive around £324 million in sales for M&S in the first half of the year to September, with the final figure resting at £184.1 million, down from £413.1 million a year earlier.

Despite the hit, the retailer has managed to rebound with an upswing in revenue across the business. Total group sales rose 22.1% to £7.97 billion during the year’s first half, buoyed by a strong performance in the food division, which recorded 7.8% growth and underscores resilience as consumers continued to trade up within M&S’s quality-focused grocery offer.

Chief executive Stuart Machin said: “The first half of this year was an extraordinary moment in time for M&S. However, the underlying strength of our business and robust financial foundations gave us the resilience to face into the challenge and deal with it. We are now getting back on track.”

The company confirmed that “profit performance for the half year was heavily distorted by the one-off impact of the incident and related recovery costs”. This includes “lower online sales and increased stock management costs in fashion, home & beauty and higher markdown and waste in food.”

M&S expects the full-year operating profit impact of the cyber event to be around £300 million, partly offset by a £100 million insurance recovery. The group is now accelerating investment in digital security, systems resilience and automation across its logistics network.

“We are confident we will be recovered and back on track by the financial year-end. In the second half we therefore anticipate profit at least in line with last year, as the residual effects of the incident continue to reduce in the coming months,” Machin concluded.