Retail sales in the U.K. fell more than expected in September, with food store sales logging the biggest decline in nearly three years.

Sales volume fell 0.8% month over month in September, following an upwardly revised increase of 0.4% in August, the Office for National Statistics, or ONS, said. The Econoday consensus forecast sales would slip 0.3% in September.

Sales volume in food stores declined 1.5%, the largest decline since October 2015.

In the three months to September, retail sales volume increased 1.2% from the prior three-month period. Growth was attributed to robust sales in "other stores" and online retailing.

"Retail continued to grow in the three months to September with jewelry shops and online stores seeing particularly strong sales. This was despite a stark slowdown in food sales in September, following a bumper summer," said Rhian Murphy, ONS head of retail sales.

On an annual basis, total sales volume rose 3.0% in September, following a revised 3.4% year-over-year growth in the prior month.