Discounts and promotions led to clothing and footwear prices falling in May, as shop prices for non-food items went down 1.5%.
Retailers overall reported deflation for the first time in more than three and a half years, falling 0.1% after a 0.4% rise in April according to the latest figures from the British Retail Consortium (BRC).
The drop in non-food prices was even greater, with deflation at 1.5% in May, an acceleration on the 1% deflation seen in April.
Non-food deflation is at its highest rate since June 2009 when prices fell 1.9%.
The BRC said the unsettled weather continued to affect the clothing and footwear sector, which led to a greater use of discounts and promotions, particularly on spring products, to stimulate demand while marked down knitwear was displayed longer than normal.
BRC director general Helen Dickinson said: “Non-food deflation accelerated to its highest level in almost four years, a reflection of the intense competition to capitalise on improving consumer confidence and the late onset of warmer weather.”