The Co-operative Group's Somerfield stores are "losing sales across the board", according to the latest Kantar Worldpanel data.

Somerfield sales were down 50.5% year-on-year for the 12 weeks to 16 May. Much of this can be accounted for by the sell-off of stores, but the remaining stores are also losing share.

"The Co-op is losing Somerfield sales to everyone, not just to those who bought stores," said Kantar Worldpanel's Edward Garner. "Asda, Aldi, Iceland and even the independents are making gains. The Co-op is aware it has an issue with older Somerfield shoppers who don't like change."

Data seen by The Grocer earlier this month showed like-for-like sales in former Somerfields converted to The Co-operative fascia down 12.2% year-on-year.