ISRAEL has allegedly increased its nuclear weapons stockpile by adding an additional 10 warheads to its arsenal, according to the Stockholm International Peace Research Institute (Sipri).

The global arms watchdog released a file showing that Tel Aviv has 90 nuclear missiles this year, up from the 80 it was believed to have held in 2019.

But Sipri warned that the secretive nature of the Israeli nuclear programme meant that the true figure was likely to be higher.

“There is significant uncertainty about the size of Israel’s nuclear arsenal and its warhead capabilities,” the report said.

Tel Aviv refuses to comment on its nuclear capabilities and failed to sign the 1968 Non-Proliferation Treaty (NPT).

“Israel continues to maintain its long-standing policy of nuclear opacity: it neither officially confirms nor denies that it possesses nuclear weapons,” Sipri commented.

Although the country goes to great lengths to conceal details of its capabilities, there was an important leak in 1986 when former nuclear technician Mordechai Vanunu passed details of the Israeli nuclear weapons programme to the British press.

Mr Vanunu was subsequently lured to Italy, where he was drugged by Mossad agents who took him back to Israel. Following a trial held behind closed doors, he was jailed for 18 years. The peace activist spent 11 years in solitary confinement and was released in 2004.

Israel is believed to have started developing its programme in the 1960s with US assistance.

Last year, the Morning Star reported on declassified documents showing that then US president Jimmy Carter covered up a nuclear test conducted by Israel in the southern Indian Ocean in September 1979 for fear that it would have damaged his re-election campaign.

Sipri said that the locations of the storage sites for Israel’s warheads, “which are thought to be stored partially unassembled,” are unknown.