An internal investigation is continuing into the technical problems which forced the cancellation of Wednesday night’s Lotto draw for the first time in the lottery’s history.

Premier Lotteries Ireland (PLI) was forced to postpone the draw for 24 hours after a "telecommunications outage" knocked out most ticket terminals across the country for much of Wednesday. Customers were unable to buy tickets for the €10 million-plus jackpot, the biggest in eight months.

PLI, which only took over the running of the Irish lottery last November, blamed the problem on its telecoms provider, Telefónica.

However, industry sources said while the outage may have trigged the problem, it should not have resulted in such a prolonged disruption to the service. It took technicians from 9am on Wednesday until after 6pm to restore service to retailers.

Some sources have claimed the lottery's own system, which was recently switched from a fixed-line broadband account with Eircom to a cheaper 3G mobile contract with Telefónica, was not properly backed up.

PLI chief executive Dermot Griffin denied the lottery's system was at fault, insisting a number of other businesses were affected by the Telefónica problem.

He also denied the switch to a wireless network had anything to do with the problem or that the change was motivated by a desire to cut costs.

Mr Griffin admitted, however, there was a question as to why “system failovers” - which should have switched the system to a back-up during Wednesday’s outage - failed to kick in.

He said the company was still investigating the incident and had requested a report from Telefónica.

The PLI consortium, comprising An Post and the Ontario Teachers’ Pension Plan (OTPP), owners of British operator Camelot, was already facing criticism over its roll-out of new ticket terminals late last year.

Retailers say the new machines, supplied by Greek gaming firm Intralot, have been plagued with technical glitches and are not interfaced with separate ticket checkers in shops, which is causing delays and a noticeable drop in sales.

Mr Griffin said Wednesday’s problems, however, were entirely unrelated to the roll-out of new terminals.

Retailers' umbrella group RGData has called on the new National Lottery regulator, Liam Sloyan, who has only been in the job three months, to investigate the problems which led to the cancelling of Wednesday's draw.

"RGData is very concerned with the length of time it took to get service back to retailers for the National Lottery. It is unacceptable that retailers should suffer a loss of service for a full day," the group's director general Tara Buckley said.

“Retailers are frustrated at the disruption and inconvenience to their businesses and their customers. We are surprised that the National Lottery didn’t have a contingency plan in place,” she added.

The National Lottery’s director of marketing Eddie Banville said Wednesday’s problems happened “on the worst possible day” for the franchise with a jackpot of €10 million at stake - the highest since last May.

He said the decision to postpone the draw until last night was made to provide frustrated punters with access to the system.

Last night’s draw went off without a hitch.