OTTAWA – Canadian retail sales unexpectedly fell in August, due in part to the biggest month-over-month drop in purchases of food and beverages in nearly three years.

A solid gain in auto-related transactions and the first gain for gasoline stations in four months weren’t enough to stop retail sales from posting their steepest drop since March of last year.

The value of retail sales in August declined 0.3% on a seasonally adjusted basis to 48.93 billion Canadian dollars ($39.21 billion), Statistics Canada said Friday. Market expectations were for a 0.5% gain, according to economists at Royal Bank of Canada. On a year-over-year basis, retail sales rose 6.9%.

Excluding the auto component, August retail receipts fell…