Minimum prices for beer and spirits sold in Ontario are going up starting March 1.

The increase will only affect 1.5 per cent of alcohol products sold in the province through the Liquor Control Board of Ontario's beer and wine stores.

Wines won't be affected because none of its wines are sold at the minimum price, said LCBO spokesman Chris Layton.

About 10 per cent of spirits sold by the LCBO and three to four per cent of beers will see their prices go up.

A 24-bottle case of the cheapest beer will go up by 55 cents, from $28.80 to $29.35. A 750 mL bottle of a mainstream spirit will go up by 50 cents to $23.90.

"Consumers will see very little change on March 1," Layton wrote in an email.

The Crown corporation is required to set minimum prices as part of its commitment to social responsibility.

But NDP Leader Andrea Horwath called the hike a "literal example of consumers being nickel and dimed."

"Sure, there is room for the LCBO to generate more revenue," she said.

"But the (auditor general) was pretty clear this can come from leveraging its buying power. It doesn't have to come out of the consumer's pocket."

Last month, auditor general Jim McCarter took the LCBO to task for failing to use its massive buying power to negotiate lower wholesale prices.

He noted in his annual report that on occasion, if suppliers submit significantly lower quotes than the LCBO expects, it will ask the suppliers to raise their wholesale price.

But if the LCBO used its power as one of the biggest buyers of alcohol in the world to obtain lower wholesale prices, it could then assess whether paying those lower prices would still allow it to increase its profit margins and meet its retail price objectives, he said.

The LCBO has defended its pricing policy, noting that it returned $1.5 billion to the provincial treasury in 2010-11.