Troubled supermarket group Morrisons has plunged into the red, revealing a hefty pre-tax loss in its half-year results.

Releasing its interims for the 25 weeks to July 24 this morning, Morrisons reported a pre-tax loss of £73.7m, compared with a profit of £121.6m for the same period last year.

Like-for-like sales in the core Morrisons estate for the 12 weeks to October 16 were down 5.2% excluding fuel. Operating profit dropped from £168.9m to £50.7m.

“Inevitably, in a period of great change, the underlying trading picture has been difficult to read. In addition, the market backdrop has been exceptionally competitive,” Morrisons said.

The group also revealed that the process of converting Safeway stores to Morrisons was “continuing at pace”, with 90 Safeway stores converted to the Morrisons format during the period.

Sir Ken Morrison, chairman of Morrisons, added: “Converted stores saw a 23% increase in customers. Optimising our performance in the newly converted stores and throughout the business will provide real opportunities for material improvement.”

Morrisons has also started the search for a new chief executive officer to replace Bob Stott who will leave the group next year. The group added that Stott would remain in the role until the succession issue was determined.