But a fall in food prices led to lower inflation in shops last month. The overall rate of shop-price inflation fell by 0.3% between February and March, but it remained high at 2.4% last month.
The overall figure was driven downwards by a reduction in food inflation, which fell to 4% in March, down from 4.5% the previous month thanks to sales promotions.
BRC director general Stephen Robertson said: "Global commodities are still exerting considerable upward pressure on retailers' costs, but a greater intensity of promotions has led to a fall in year-on-year food inflation, which will come as a great relief to hard-pressed families.
"Over the shorter term, food was actually cheaper in March than February. It's a clear demonstration of competition in the retail sector keeping costs down for shoppers."