The Tanaiste has said he is open to an independent investigation being carried out into the exclusion of four prizes from the National Lottery.
The National Lottery apologised on Wednesday after it emerged four top prizes totalling €180,000 from three scratch card games dating back to 2014 had been excluded.
Lotto operator Premier Lotteries Ireland (PLI) found the prizes were not included for players to win in three out of 178 scratch card games the National Lottery had offered since taking over the licence in 2014.
The mistake was blamed on "human error" and was discovered following an internal review of all National Lottery products over the last six weeks.
Fianna Fail has called for PLI to appear before an Oireachtas Committee to explain how the incident happened.
Speaking during Leaders' Questions in the Dail on Thursday, Simon Coveney said he was open to an independent investigation being carried out as the integrity of the lottery system needed to be protected.
He echoed calls from Fianna Fail that the regulator and PLI should appear before the committee "to get to the bottom of this".
Sinn Fein TD Pearse Doherty described how four top prizes being left out of lottery games was "unbelievable".
He said the private operator PLI wrote its own code of conduct and that legislation needed to change and an investigation should be carried out.
He said the probability of the jackpot prize being missing was "one in a million" but the issues raised serious questions about the National Lottery.
"This company has made enormous profits. There is a serious issue in relation to the regulator. It has a team of 10. There is a serious question in relation to the role of the regulator," he added.
Mr Doherty said it was not right that the National Lottery continued to allow people to purchase the scratch cards up to this week, despite knowing the prize fund structure was not in line with what is approved by the regulator.
In a statement on Wednesday, the Office of the Regulator of the National Lottery confirmed it became aware of the errors last month.
The regulator said: "My office has become aware of anomalies in three scratch card games, relating to four omitted jackpot prizes."
