The regulator said the issue may have contributed to 394 prizes, worth a total of up to €2,299, going unclaimed, RTÉ News reports.

A third-party software update between September and October 2022 meant that some players were able to access a “Check My Numbers” page on the National Lottery website when the numbers had not yet been confirmed.

As a result, some players may have been wrongly told that their ticket was not a winner, when in fact they may have won a prize of up to €250.

Premier Lotteries Ireland (PLI) self-reported the issue to the regulator, which found that it had breached its licence.

Carol Boate, the lottery regulator, said: “While unclaimed prizes are a feature of all lotteries, it may be that some 394 ticket holders relied on a ‘not a winner’ message from the Check My Number Facility online, which did not yet have details of the latest draw to check against the numbers entered by players.

“Every breach is a serious matter for my office as reflected in my decision to withhold €23,000 in funds from the operator and ensure a permanent technical solution to my full satisfaction.”

She added: “I do not underestimate the potential impact that this technical error could have had on a larger prize winner.”

A spokesperson for Premier Lotteries Ireland said: “Premier Lotteries Ireland (PLI) acknowledges the decision by the Regulator of the National Lottery (RNL) to find a licence breach linked to the ‘Check My Numbers’ functionality on the National Lottery website in 2022.

“The issue was discovered by PLI and self-reported to the RNL. 

“PLI can confirm that it did not receive any customer complaints in relation to this isolated incident nor were unclaimed prize rates above normal levels.

“However, PLI has paid into the top up prize fund a sum equivalent to all expired unclaimed prizes potentially impacted. PLI has introduced a permanent solution and can confirm that the issue has not recurred.”