Food inflation increased to 4.9% in May, representing the highest rate since June 2009.
The figrure compares with 4.7% recorded in April, according to the BRC-Neilsen Shop Price Index.
The BRC said the increase was due to the rising cost of key commodities such as wheat and oil.
Shop price inflation slowed to 2.3% in May from 2.5% in the month before.
Non-food inflation slowed for the fourth consecutive month according the BRC-Neilsen Shop Price Index. It stands at 0.8% down from 1.2% in April. BRC director general Stephen Robertson said the drop reflected weak demand in the sector.
He said: “Even though the VAT rate went up 2.5% in January, non-food goods are less than 1% higher than last year - reflecting weak demand and retailers’ need to use promotions and discounts to generate sales.”
Neilsen senior manager, retailer services Mike Watkins warned that promotions were not a long term answer to weak consumer demand.
He said: “Inflation and other rising household bills are still top of mind for shoppers so retailers are offering more promotions and deeper price cuts.
“This continues to be an important driver of sales for retailers and a coping strategy for shoppers but should not be seen as the long term answer to any weakening of consumer demand or falls in consumer confidence.”