The Tanaiste, Ms Harney, has suggested that the supermarket chain Tesco refund money to consumers who were overcharged on purchases by the store.

She also indicated the possibility of prosecution but said that the investigation into overpricing by Tesco was a matter in the first instance for the Director of Consumer Affairs.

Ms Harney, as Minister for Enterprise, Trade and Employment, said that she was not sure how Tesco might refund the money "but it is a serious matter". She was given an assurance that it would be rectified by the weekend.

Referring to figures quoted by Mr John Perry (FG, Sligo-Leitrim) that 26 per cent of net family income was spent on groceries, she said it was a high percentage.

Mr David Stanton (FG, Cork East) asked if the Minister was aware of the consternation and anger at the revelation that Tesco had been overcharging.

He questioned the Minister's assertion that the overcharging was accidental. "My colleague said that £33 million had been taken out of consumers' pockets in one year. That is staggering by any standards. It amounts to £500,000 a week."

Ms Harney said she did not have the power to "go around giving the money that was overcharged back to people".

Mr Pat Rabbitte, Labour's Enterprise, Trade and Employment spokesman, said that the issue could not be left without the necessary prosecutions, given the level of the "suspected fraud on consumers", and it could not be left to the marketplace to correct the fault, whether it was intentional or unintentional.

Ms Harney said there was "much merit" in what Mr Rabbitte was saying. "It is not enough to say it was a mistake, it will not happen again and we will move on from here. The company in question should be seen to reimburse their consumers. Perhaps that is something we can explore with the company. If the sum is as large as £33 million or £500,000 a week, it is a considerable amount of money. It is more than the turnover of many in the retail trade nationally." Asked about "hello money" Ms Harney said that the Government wanted to prohibit such payments and ensure that there was no below-cost selling. She suggested that the penalties for a breach of the Groceries Order were too small - a fine of up to £500 or six months in jail. In the past decade about 10 breaches of the order had been investigated and three had gone to court.

The Minister said she would ask the Director of Consumer Affairs to examine all the matters.