Tánaiste and Minister for Foreign Affaris Simon Coveney has said there needs to be an independent investigation into the exclusion of four prizes from the National Lottery.

Operator PLI apologised after it emerged the prizes valued at €180,000 were excluded from three of its 178 scratch card games since 2014.

Speaking during Leaders' Questions in the Dáil, Mr Coveney added that the integrity of the lottery system needed to be protected and there needed to be an independent investigation.

He said the regulator and the operator needed to appear before an Oireachtas committee "to get to the bottom of this."

Mr Coveney was answering questions from Sinn Féin's Pearse Doherty who said that the probability of the jackpot prize being missing was "one in a million."

He said: "This company has made enormous profits. There is a serious issue in relation the regulator. It has a team of ten. There is a serious question in relation to the role of the regulator."

Earlier, speaking on RTÉ's Morning Ireland, Mr Doherty said the regulator had failed in its duty to uncover the error, despite having access to data at the National Lottery.

He said it was not right that the National Lottery continued to allow people to buy the scratch cards up to this week, knowing the prize fund structure was not in line with what is approved by the regulator.

He said that 1.5 million scratch cards were printed in three different games and four cards that were not printed "happened to be cards with the top prizes", which he said was "deeply suspicious".