Sainsbury’s is now selling a pint for £1.05 in small shops while two pints cost £1.35.
Shoppers are now paying two and a half times more for milk than a year ago.
In Sainsbury’s bigger stores it costs almost a fifth less at 85p for a pint and £1.15 for two.
Just a year ago the price of an average pint of milk was 43p, according to official figures.
Last month Sainsbury’s raised dairy prices overall by 10 per cent.
At Tesco the price for one pint of milk is the same in both its bigger and smaller shops at 85p — as it price matches with Aldi.
All UK supermarkets bumped up the price of milk last month after dairy farmers said that soaring costs of feed, fertiliser and fuel meant they were struggling to survive.
Farmers say the cost of producing milk is now 44p per litre, compared to 23p a year ago.
Sainsbury’s said: “There may be price differences between convenience stores and supermarkets.
“This is because our Sainsbury’s Local stores are located in city or town centre locations and their operating costs, for example rent and rates, are higher.”
Higher dairy prices have been one of the biggest drivers of food inflation – now at 12.8 per cent.
Prof Tim Lang, of City, University of London, yesterday warned Times Radio the crisis in food prices is now close to the 1840s and “right up here” with the 1970s.