The Tánaiste, Ms Harney, has been urged to review the pricing practices of supermarkets following the publication of a survey showing them retailing lamb meat at up to twice its wholesale price.
Dr Mary Upton TD, the Labour Party spokeswoman on food safety and consumer affairs, said the Tánaiste should intervene to protect the consumer from "profiteering".
She was commenting on an Irish Farmers' Association survey which claimed sheep farmers were receiving less for an entire lamb than Marks & Spencer in Liffey Valley, Dublin, charged the consumer for 2 kg of rack of lamb.
The survey cited similar instances in other supermarkets where, it said, consumers were being "fleeced".
Describing the revelations as "shocking", Dr Upton said: "They show that some supermarkets are increasing the price of lamb by up to 100 per cent more than the cost paid to the meat factories, a profit which is being gained at the consumer's expense.
"This type of profiteering should not be allowed to continue and the Tánaiste should investigate how and why it is happening."
She added: "The potential damage of this information is twofold. On the one hand, the consumer is being hit by huge price increases for lamb, which will turn people off buying lamb products and undermine consumer confidence in the meat industry.
"It may also have the effect of damaging the confidence of lamb producers in the retail industry."
According to the survey, supermarkets were charging consumers €8-€10 a kg for lamb leg; €5-€7.50 a kg for shoulder and €14-€18 a kg for loin chops.It claimed farmers received just €3.30-€3.40 a kg for lamb from the meat factories.They in turn sold lamb leg to supermarkets at €4.30 a kg; shoulder at €3 a kg; and loin chops at €7.40.