Consumers in the Republic of Ireland are paying more for their groceries than people in the expensive holiday resort of St Tropez in the south of France, according to a survey.

The study by online newsletter 'Retail Intelligence' found a shopping trolley of 40 items of food and drink in the Irish Republic cost �197.54 (296.31 euro) compared with �155.21 (232.82 euro) in the south of France.

Rising costs of everyday grocery and drink items has prompted the deputy prime minister, Mary Harney, to encourage shoppers to use their purchasing power to force down prices.

Mary Harney: "We need to equip consumers with more information"

Ms Harney said indirect taxation and insufficient competition were partly to blame for the price differences.

"We need also, of course, to develop a stronger consumer culture and to equip consumers with more information," she said.

"As consumers, we do have to be more vigilant and use the collective power and purchasing power we have perhaps more wisely."

Despite it being the home of Guinness, a 500ml can of the drink costs �1.39 (2.09 euro) in Ireland compared with just 88p (1.32 euro) in France.

I am looking for a statement by the retailers in Ireland as to what their margins really are

Carmel Foley Director of Consumer Affairs

Ireland's Director of Consumer Affairs, Carmel Foley, said the difference in costs could be explained by a larger French population which meant goods were bought in greater bulks.

"But of course that is not the whole story and that is why I am looking for a statement by the retailers in Ireland as to what their margins really are," she said.

However, the independent grocers' group, RGDATA, has questioned the accuracy of the findings.

Different tax regimes, consumer tastes, product quality and size, and Ireland's position as an island, all affected costs, the group said.

Director General Ailish Forde said: "Cross border surveys do not provide an accurate way of measuring consumer food prices across Europe.

"They certainly cannot be used as a basis for claims that consumers are being ripped off."