Retailers last month suffered their biggest annual fall in like-for-like sales since May, as widespread discounts failed to lure in pre-Christmas shoppers, the British Retail Consortium said on Tuesday.

The value of retail sales on a like-for-like basis -- a measure favoured by equity analysts -- was 1.6 percent lower than a year ago after a 0.6 percent fall in October, worse than the 0.7 percent fall forecast in a Reuters poll.

The total sales measure -- which unlike the like-for-like metric includes new floorspace, and is closer to the measure used in Britain's official statistics -- also showed the weakest annual growth for six months. Total sales grew by just 0.7 percent, down from a 1.5 percent annual rise in October.

With inflation running at 5 percent, retail sales volumes are almost certainly significantly down on a year earlier.

Consumers are not quite in the Christmas mindset yet, although stores are working to generate much-needed sales with high levels of festive discounting, said Stephen Robertson, director general of the BRC.

This November's mild weather contrasted with much lower temperatures last year, hitting sales of winter clothing and footwear particularly hard, he added.

Retailers have been struggling as consumers rein in spending in response to below-inflation pay rises, higher taxes, rising unemployment and low confidence.

Official data showed that sales volumes rose by a surprisingly decent 0.9 percent on the year in October, but that was driven by widespread discounting in the run-up to Christmas.

The BRC's three-month weighted average showed that food sales were up 1.5 percent on a like-for-like basis between September and November compared to the same period in 2010, but non-food sales were down 2.1 percent.

Christmas is a crucial trading period for the UK retail sector but this year many retailers will be nervous and unsure as to how the season will pan out, said Helen Dickinson, head of retail at accountants KPMG which co-authored the survey.

(Reporting by Olesya Dmitracova; editing by Ron Askew))