Iran is just a few weeks away from having enough fissile material for a nuclear bomb, Israel’s defence minister has warned.

Speaking on Tuesday, days before flying to the US for a summit on the threat from Tehran, Benny Gantz said: “Iran continues to accumulate irreversible knowledge and experience in the development, research, production, and operation of advanced centrifuges.

“It stands just a few weeks away from obtaining fissile material needed for a first bomb.”

The minister was speaking at an Institute for Policy and Strategy conference at Herzliya’s Reichman University, ahead of a simulated attack on Iran in an IDF exercise later this month.

Mr Gantz said that Iran currently holds about 60 kg of 60 per cent-enriched uranium, which is almost twice as much as the 33.2 kg estimated by the UN International Atomic Energy Agency (IAEA) in its report in March.

He also addressed concerns over Iran’s capacity to build centrifuges, which are crucially used in the processing of nuclear substances to achieve weapons-grade material. Tehran is believed to keep a large number of them in the Natanz nuclear plant, in an underground facility where they are protected from air strikes.

He said: “During these very days, Iran is making an effort to complete the production and installation of 1,000 advanced IR6 centrifuges at its nuclear facilities, including a new facility being built at an underground site near Natanz.”

The estimate is significantly higher than that given by the IAEA in March. The nuclear watchdog said that Iran had installed, or planned to install, some 660 centrifuges.

Gantz was speaking ahead of his scheduled meeting in Washington DC on Thursday with his American counterpart, Defence Secretary Lloyd Austin, with discussions due to cover Iran and the war in Ukraine. Tehran’s nuclear programme is also expected to be a top priority next month when US President Joe Biden makes his first official visit to Israel since taking office.

Rouhani and Salehi in Bushehr Nuclear Plant (1)

Ominous progress: Iran President Hassan Rouhani and atomic chief Ali Akbar Salehi at one of its nuclear plants (Photo: Getty Images)

Last week, EU’s Foreign Policy chief Josep Borrell said that nuclear negotiations between Iran and world powers had been “de-blocked” after being stalled for weeks. One of the key issues that prevents the parties from signing a new nuclear deal is Washington’s refusal to delist Iran’s Revolutionary Guard Corps as a terror group.

Israel has said repeatedly that it will do everything it takes to prevent Iran from acquiring nuclear weapons, but that it vehemently opposed a nuclear deal with Tehran.

Prime Minister Naftali Bennett claimed in February that such a deal would “likely create a more violent, more volatile Middle East,” by pouring “billions of dollars, into the Iranian terror machine”.

Last month, Gantz said that in case a nuclear deal isn’t reached, a “Plan B must be used: to use force, to exert economic pressure, to exert political pressure.” The Israeli air force is expected to simulate a wide-scale attack on Iran on 29 May as part of its month-long “Chariots of Fire” military exercise, according to Israeli media.

“Chariots of Fire” began last week, and involves almost all units in the army, on land, air, sea and in cyberspace.

The exercise “aims to both increase the IDF’s defensive readiness and examine its preparedness for an intensive and prolonged campaign”, an IDF statement read.

The simulated attack against Iran will take place in Cyprus, and is also expected to include preparation for retaliation from Iran.

While Israel has threatened Iran with military attacks against its nuclear programme, some experts have advised it, claiming the strategy is not realistic. They include former prime minister Ehud Olmert in an interview with the JC earlier this month.

In December, The New York Times quoted a current senior security official as saying that Israel does not have the ability to inflict any significant damage to the underground nuclear plants Natanz and Fordow.