President Putin begins an historic visit to Iran today - a visit already overshadowed by allegations that suicide bombers plan to assassinate him.

The Russian President is defying security service warnings about a possible attempt on his life to arrive in Tehran for a two-day visit, the first by a Kremlin leader since Joseph Stalin in 1943. “If I listened to all the various threats and the recommendations of the special services I would never leave home,” Mr Putin said at a summit in Germany with Angela Merkel, the Chancellor, before boarding his flight to Iran.

Kremlin officials had suggested yesterday that the visit could be cancelled after reports emerged that as many as three teams of suicide bombers and kidnappers in Iran were conspiring to kill or capture Mr Putin.

Tehran denounced the claim as a form of “psychological warfare” waged by Iran’s enemies to undermine its relationship with Russia before a crucial visit. Russia is one of the few countries that maintains good relations with the regime of Mahmoud Ahmadinejad, the Iranian President.

Mr Putin is in Tehran to attend a conference of Caspian Sea nations today to divide up the energy-rich basin with the leaders of Iran, Azerbaijan, Kazakhstan and Turkmenistan. He will also hold private talks with Mr Ahmadinejad over Iran’s nuclear ambitions, a meeting that will be scrutinised closely by other big powers.

The United States and Europe are pressing for tougher United Nations sanctions against Iran as speculation mounts over a possible military strike to prevent Tehran acquiring a nuclear bomb. Mr Ahmadinejad insists that Iran’s nuclear programme is for peaceful civilian energy purposes.

Russia has opposed further sanctions and warned against military action, a stance repeated yesterday by Mr Putin. He said that his visit offered an opportunity for diplomacy to find a way out of the crisis, as it had done in persuading North Korea to decommission its nuclear reactor.

“We were patient and consistently looked for solutions and it looks like we are finding them,” Mr Putin said. “The same has to be applied, we believe, in the case of the Iranian nuclear programme.”

It was pointless to try to intimidate Iran into compliance, he said, and added: “They are not afraid.”

Russia is far more sceptical than the US about Iran’s nuclear ambitions. It is building Tehran’s first nuclear reactor at Bushehr, but a dispute over payments has delayed its completion. Mr Putin has promised to press Mr Ahmadinejad to cooperate fully with inspections by the International Atomic Energy Agency.

The Interfax news agency broke news of the possible assassination plot late on Sunday, quoting a security service source.

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