A person in the western Morbihan region suffering from a heart condition was reported dead after failing to put through an emergency call during the outage which lasted for several hours on Wednesday, Interior Minister Gérald Darmanin said.

While it was not certain that the death was caused directly by long delays in getting through, “what is beyond doubt is that people have told us that they tried calling several times and that they couldn’t get an operator immediately,” he told reporters.

Two people with heart conditions in the overseas territory of La Réunion were also reported dead.

Calling the outage a “serious and unacceptable malfunction”, Darmanin said that Stephane Richard, the CEO of Orange which is France’s biggest telecom company, had been summoned early on Thursday to his ministry “to tell us the current state of play”.

Darmanin reported on Wednesday evening that some emergency call centres “are having difficulty receiving calls due to a technical problem from the operator”.

“Everything is being done to resolve these malfunctions as quickly as possible,” he tweeted.

By Thursday morning the emergency numbers – 17 for police, 15 for ambulance, 18 for firefighters and 112 for all emergencies – were back up and running, although temporary numbers set up overnight were also left in place.

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Health Minister Olivier Véran said the breakdown was “obviously due to a maintenance problem” by French telecoms group Orange.

The maintenance carried out “by Orange would have caused fairly random breakdowns, with up to a 30-percent drop in some regions”, Véran told the TF1 channel.

Orange confirmed to AFP that a “technical incident on a router had greatly disrupted VoIP (voice over internet protocol), internet calls in some regions”.

A source close to the case ruled out any kind of “hacking”.

Problems were reported across the country from 6pm, causing havoc for emergency services.

Emergency doctor and head of the Samu-Urgences emergency medical services union François Braun said “people were unable to access the service, calls were not coming through, others were cut off in the middle of a conversation”.

He said that almost all of France’s departments were affected, adding that calls usually peak around 7pm.

“We don’t know what consequences this breakdown will have, it’s too early to say,” he said.