Israel's Prime Minister Benjamin Netanyahu has handed the Kremlin a list of Russian scientists believed by the Israelis to be helping Iran to develop a nuclear warhead. He is said to have delivered the list during a mysterious visit to Moscow.

Netanyahu flew to the Russian capital with Uzi Arad, his national security adviser, last month in a private jet.

His office claimed he was in Israel, visiting a secret military establishment at the time. It later emerged that he was holding talks with Vladimir Putin, the Russian prime minister, and President Dmitry Medvedev.

“We have heard that Netanyahu came with a list and concrete evidence showing that Russians are helping the Iranians to develop a bomb,” said a source close to the Russian defense minister last week.

“That is why it was kept secret. The point is not to embarrass Moscow, rather to spur it into action.”

Israeli sources said it was a short, tense meeting at which Netanyahu named the Russian experts said to be assisting Iran in its nuclear program.

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