Fine Gael has published a survey suggesting that Irish consumers are being charged up to four times the price farmers are paid for some of their produce.
The study compared the prices Irish farmers receive for nine basic products and the prices charged for these products by three main supermarket chains.
It found that, on average, supermarkets were charging 119 per cent more for the products than what farmers were paid.
It was the latest in the party's campaign to raise price awareness in Ireland, and survey prices in three supermarket chains: Tesco, Dunnes Stores and Superquinn. The party has set up a website - www.ripoff.ie - to take complaints from the public about prices.
The largest mark-up was for potatoes. Farmers receive 20 cent per kilo, while Tesco was charging 90 cent for a kilo of a similar product, Superquinn 80 cent and Dunnes Stores 70 cent. Poultry farmers receive 64 cent for 12 eggs, while the supermarkets charged between 1.48 and 1.59.
Farmers receive an average of 3.44 per kilo of beef, according to Fine Gael, compared with an average of 8.37 charged in supermarkets. The survey found that lettuce cost 79 per cent more in the three supermarkets than the amount received by farmers. Other mark-ups include 126 per cent for milk, 155 per cent for cabbage, 181 per cent for cauliflower, 193 per cent for carrots and 32 per cent for mushrooms.
Mr Billy Timmons, Fine Gael's agriculture spokesman, called for an independent study into the cost of food in Ireland.
"Fine Gael's consumer website has received numerous complaints about high food prices. In the past seven years, CSO figures show that food prices have risen by 26 per cent, but farm gate prices have hardly risen at all."
However, representatives of the retail industry have rejected any suggestion they are overcharging.
Mr Turlough O'Sullivan of Retail Ireland, a wing of the employers' body IBEC, said the prices charged in supermarkets reflected the large increases in costs, such as labour and insurance, which supermarkets have experienced in recent years. "We are now an expensive country to do business in," he said.
Mr Eamon Quinn, deputy chairman of Superquinn, described the mark-up figures as "a misnomer", saying the net profit rate of supermarkets, when all costs are taken into account, were extremely low.