The Co-operative Group has blamed difficulties integrating Somerfield for a 2.5% fall in full-year like-for-like food sales.

Total sales in its food business rose 4.8% to £7.5bn in the year to ­1 January, with operating profits up 33% to £382.6m.

CEO Peter Marks said like-for-likes were down because of "disruption" caused by Somerfield. The society had closed 25 stores every week to convert them to the Co-op fascia, and systems and distribution process were also being overhauled. There were now just "60-ish" stores left to convert.

"Natural churn" meant the society was selling 40 stores, but Marks said that the society planned to open 350 new stores over the next three years.

He also laid out plans to increase the percentage of all fresh produce from The Co-operative Farms from 6% now to 25% by 2015.