BT Ireland has apologised after a technical issue prevented callers accessing the Emergency Call Answering Service for over an hour yesterday.

The service handles 112 and 999 calls and texts connecting people with gardaí, as well as fire, ambulance and coast guard services.

BT Ireland has a contract with the Government to operate the service.

"A technical issue prevented callers accessing the Emergency Call Answering Service from 1am to 2.15am on Tuesday 28 June," a company spokesperson said.

"We quickly restored the service and provided gardaí with the list of callers so that they could call them directly and offer help."

"We apologise unreservedly to any caller who may have been affected by this service issue," BT Ireland said.

The Department of the Environment, Climate and Communications says the outage affected approximately 227 callers and that they were all subsequently followed up by gardaí.

Nine of the calls were test calls, while two resulted in gardaí still to be required and these are being progressed.

Eighteen numbers were uncontactable, 140 of the calls were not answered when called back and 58 no longer required the gardaí or were ringing in the first instance for other emergency services.

The Department said it understands, from early incident reports from BT Ireland, that the incident resulted from a technical operational issue, which the company moved to rectify quickly.

"The cause of the incident is not believed to have been malicious in nature," a department spokesperson said.

Minister of State with responsibility for Communications, eGovernment and Circular Economy Ossian Smyth, who has been briefed on what happened, said the department has now sought a detailed and comprehensive report from BT Ireland on the incident.

Mr Smyth said the immediate priority is to ensure there is no risk of a similar occurrence in the future.

He said the department will establish the precise circumstances that gave rise to the service outage and then, in consultation with its legal advisers, determine the consequences under the contract.

"We've operated the Emergency Call Answering Service on behalf of the Department of Environment, Climate and Communications for more than 12 years, transforming it into one of the top performing emergency call handling services in Europe," BT Ireland said.

"It is a responsibility that we take with the utmost seriousness, and we'll continue our relentless focus on meeting the high standards expected of us by DECC and the citizens of Ireland."

Meanwhile, the head of the Irish Patients Association said he would like the Minister for Health to carry out his own investigation into the issue.

Stephen McMahon said it was crucial that the country had a "robust, secure" system in place, adding that an incident like this has the potential to seriously impact confidence.

He also said he would like to see a breakdown of how many of the calls affected related to medical emergencies.

Sinn Féin Spokesperson on Communications Darren O'Rourke has called for clarity on the matter, and has written to the minister.

"We need absolute clarity on what went wrong - what systems failed and what back-up systems failed, and why," he said.

"I have written to the minister and to the Oireachtas Transport and Communications Committee on the matter.

"It is important that action is taken urgently and if there are breaches of contract that they are pursued. The public must be guaranteed that their calls will be taken and acted on. Anything less is unacceptable."