The figures compare well with Tesco, which reported like-for-like sales over Christmas up by 3.1%, and Sainsbury’s at 5.1%.
Morrisons, which reports next week, is expected to post growth of about 8%.
Somerfield added that for the three weeks to 5 January, its like-for-like sales (excluding fuel) were up by 6.7%.
Chief executive Paul Mason said: “Somerfield has enjoyed an exceptional Christmas. Our strong like-for-like sales growth reflects the turnaround in the business and our clear focus on delivering the local grocery offer our customers want.
“Our smaller stores performed particularly well, underlining the strength of our market position focused on convenience, the fastest-growing area of the food retail market.
“Over the past two years, our strategy has been to reshape, regenerate and grow Somerfield. We are focused on providing our customers with the best availability, the freshest product, the friendliest service locally and being the easiest local store to shop.
“In the last 16 weeks, Somerfield has outperformed the industry in 12 of those weeks, according to IGD data.
“After two years under private ownership, the business is making good progress and Somerfield is well-positioned to take advantage of its 900 great store locations throughout the UK to become Britain’s favourite local grocery shop.
“We are delighted with the progress in the business.”
