The Co-operative Group's CEO Peter Marks has accused the government of needlessly denting consumer confidence and making the economy and trading conditions worse.

Unveiling the society's half-year trading figures, which showed a 1% dip in total like-for-like food sales for the 26 weeks to 3 July, Marks warned that customers would "continue to feel uncertain because the government is frightening them to death".

The economy was unlikely to improve until late 2011 "at the earliest", he said, although he stopped short of predicting a double-dip recession.

Sales had inevitably been hit by the integration of Somerfield, Marks added. "We are modernising Somerfields at a rate of 24 a week," he said. "To modernise the stores we have to close for two to three days.

"We've got no other choice. Multiply that by 24 and of course you're going to get to the stage where it causes disruption. That's why we have decided to integrate at pace."

He refused to reveal like-for-like sales data for the Somerfield estate, but in May this year leaked data revealed sales were down 11% year-on-year in stores still under the fascia.

Marks insisted the society was on track to complete the conversion of the remaining 300 Somerfields by the first quarter of 2011.

"What gets lost in all the talk about the Somerfield integration is it is the biggest-ever undertaken in terms of store numbers," he said. "We took on about 700 stores and said we'd integrate it in two years. We are bang on track."

Key parts of the society's offer had thrived in the downturn, he added. Its basic range Simply Value and its premium range Truly Irresistible were performing "very well" and in two weeks the society would launch Dine In, a range of gourmet meals.

Total food sales rose 11.5% to £3.9bn during the period, with underlying food trading profit up 12.6% to £169.7m. Group sales rose 8% to £6.9bn, but pre-tax profits fell 31% to £169.2m due to one-off costs.