British retail sales posted a surprise fall in January as unusually snowy weather hurt food stores in particular, data showed on Friday.

The Office for National Statistics said sales volumes including automotive fuel fell 0.6 percent on the month and on the year - confounding economists' forecasts for higher sales.

The ONS said the main reason behind the falls was bad weather during the month, which led to shutdowns of some smaller grocers and drove the biggest monthly fall in food sales since May 2011.

The ONS said retail sales excluding fuel fell 0.5 percent on the month but were 0.2 percent higher than in January 2012 - much weaker than economists' forecasts for rises of 0.4 percent on the month and 1.4 percent on the year.

The figures contrast with an earlier survey by the British Retail Consortium, which showed that total retail sales rose 3 percent in January.

Besides the temporary hit from poor weather, Britons' spending power has been eroded by sticky inflation in recent years.

The Bank of England warned on Wednesday that high inflation would persist much longer than forecast only three months ago, pointing to a further fall in Britons' real wages, already at their lowest since 2003.

(Reporting by Olesya Dmitracova and William Schomberg)