IRAN’S UNDERGROUND NATANZ nuclear facility lost power earlier today, just hours after starting up new advanced centrifuges capable of enriching uranium faster.

It is the latest incident to strike the site amid negotiations over the troubled atomic accord with world powers.

As Iranian officials investigated the outage, many Israeli media outlets suggested it was a cyber attack.

While the reports offered no source for the assessment, Israeli media maintains a close relationship with the country’s military and intelligence agencies.

If Israel caused the blackout, it further heightens the tensions between the two nations which are already engaged in a shadow conflict across the wider Middle East.

It also complicates efforts by the US, Israel’s main security partner, to re-enter the atomic accord aimed at limiting Tehran’s programme so it cannot develop a nuclear weapon.

As news of the blackout emerged on Sunday, US Defence Secretary Lloyd Austin landed in Israel for talks with Prime Minister Benjamin Netanyahu and Defence Minister Benny Gantz.

Power at Natanz was cut across the whole facility, which comprises above-ground workshops and underground enrichment halls, civilian nuclear programme spokesman Behrouz Kamalvandi told Iranian state television.

“We still do not know the reason for this electricity outage and have to look into it further,” he said. “Fortunately, there was no casualty or damage and there is no particular contamination or problem.”

Asked by a state TV correspondent if it was a “technical defect or sabotage”, Mr Kamalvandi declined to comment.

Malek Shariati Niasar, a Tehran-based politician who serves as spokesman for the Iranian parliament’s energy committee, wrote on Twitter that the incident was “very suspicious”, raising concerns about possible “sabotage and infiltration”.

He said politicians are also seeking details of the incident.

The Vienna-based International Atomic Energy Agency, which monitors Iran’s programme, said it was “aware of the media reports”, but declined to comment.

Natanz was largely built underground to withstand enemy air strikes. It became a flashpoint for Western fears about Iran’s nuclear programme in 2002, when satellite photos showed Iran building its underground centrifuges facility at the site, some 200km south of Tehran.

Natanz suffered a mysterious explosion at its advanced centrifuge assembly plant in July which authorities later described as sabotage. Iran is now rebuilding that facility deep inside a nearby mountain.

Israel, Iran’s regional enemy, has been suspected of carrying out that attack as well as launching other assaults, as world powers now negotiate with Tehran in Vienna over its nuclear deal.

Multiple Israeli media outlets reported on Sunday that a cyber attack had caused the blackout in Natanz.

Public broadcaster Kan said Israel was likely to have been behind the attack, citing Israel’s alleged responsibility for the Stuxnet attacks a decade ago.

None of the reports included sources or explanations on how the outlets came to that assessment.