The total value of sales in June rose 1.5% versus a year ago, the BRC said.
The BRC data follows a number of high profile High Street casualties.
On a geographical basis, the BRC said that Wales saw the biggest fall in shopper numbers, down 11.5%, followed by the east of England, 7.1% lower.
The BRC figures contrasted with a recent CBI survey which reported that food stores suffered their worst performance for five years in February.
BBC: UK retail sales grew at fastest rate for years in February
The Office for National Statistics (ONS) has not yet published its figures for retail sales in November, but for some time it has been painting a more reassuring picture than the BRC (see chart).
Richard Dodd, from the British Retail Consortium (BRC), said there were a "good number of sensible ideas" in the report.
The BRC has told the Treasury that legislation would put a burden on business because of the need to train staff to charge for the bags.
The BRC said that the decline for the month as a whole came despite a rise of 7.5% in shopper numbers in the immediate week before Christmas.
Although retail sector employment rose 0.6% in the final quarter of 2012 compared with the same period a year earlier, all these jobs were part-time, the BRC said.
The BRC said these marked the highest like-for-like sales increases on a quarterly basis since December 2009.
But the BRC questioned the report's link between promotions and food waste, highlighting a UK government survey that showed buy-one-get-one-free offers were becoming rarer.
But although footfall numbers were sharply lower, last week the BRC said sales for the month were 1.9% higher in March than a year ago, a situation it described as "encouraging".
The British Retail Consortium (BRC) said the number of people visiting shops last month was 5.2% lower than a year ago.
Snow and low temperatures caused a 3.8% drop in shopper numbers compared with March last year, the British Retail Consortium (BRC) said.
Retail sales fell 0.4% on a like-for-like basis from the same month last year, according to the British Retail Consortium (BRC).
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