Shoppers who put off buying coats and boots because of last month's warm weather have helped to push retail sales to their weakest level for almost six years.

The monthly survey by the British Retail Consortium (BRC) and KPMG reported like-for-like sales were down 2.1 per cent, with total sales falling by 0.8 per cent, their poorest level since December 2008 excluding distortions for the different timing of Easter.

The drivers for this fall were clothing, which posted its worst decline since April 2012, and footwear, which recorded its biggest drop since March 2013. The ongoing supermarket wars were the other factor behind falling retail sales, with food prices over the last three months declining 1.7 per cent, and posting their first 12-month average decline in at least five years, dipping 0.2 per cent.

Last month, fashion giant Next warned it was likely to lower its full-year profit guidance if last month's unseasonably warm weather continued into October.

KPMG head of retail David McCorquodale said: "The prolonged Indian summer wilted retail sales in September, leaving clothing retailers hot under the collar.

"Selling woolly jumpers in warm weather is a tough ask, even for the most talented of sales staff."

The survey said that despite the impact of the driest September on record fashion retailers managed to limit the need for discounting. But Mr McCorquodale believes the supermarket sector will still have to battle tough trading conditions and said: "With a rebasing of margins in the grocery sector throughout the year, this final quarter will see sales go to those who are most focussed on their customers."

Attention will now turn to how well all products sell in the run up to the crucial Christmas period. Mr McCorquodale added: "One warm September doesn't ruin a Christmas and retailers on the whole are on a firm footing as they enter the all-important final quarter."