In an updated statement this evening (Sunday), the company said many of these customers have had power restored and it is continuing to work closely with the network operator to reconnect those off supply with vulnerable customers prioritised.

Of its 74,000 customers in the province, Electric Ireland has identified 4,500 keypad meter customers who are potentially impacted by this issue.

The company added: "These customers topped up between 30th of August from 00.00 hrs to 31st of August at 13.23 hrs. We have contacted the vast majority of them over the weekend via text message.

“Customers with a balance on their meter will remain connected until that balance is used. All customers who are currently on supply will remain connected until the end of the Friendly Credit period at 11am tomorrow morning.

"We have started to contact customers by text to let them know the actions that need to be taken, to return their meter to normal. Currently we anticipate this issue should be resolved for most customers by the middle of the week."

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In the meantime, the company advised, if a customer is without power they should contact Electric Ireland (Mon – Fri, 08:30 – 19:00) on 0800 313 4926. Outside of these hours they should contact NIE Networks on 03457 643 643.

“Customers should not top up their meter unless instructed to do so, as doing so may delay restoration of their service. Further information is available at electricireland.com/news/article/urgent-information-for-keypad-customers .

“We apologise that this technical error has inconvenienced our customers and assure them we are working to return normal service to all as soon as possible.”

In an earlier statement, Electric Ireland said some of its keypad customers were affected by an error which has capped their meter at a £10 credit limit.