WIESBADEN, Germany - President Vladimir Putin insisted on Monday he would make a historic trip to Iran to discuss its nuclear programme, scotching doubts about whether a reported assassination plot would force him to cancel.

"Of course I am going to Iran," Putin told a news conference after talks with German Chancellor Angela Merkel. "If you react to various threats and recommendations of the security services, then you should sit at home".

Kremlin officials had earlier said plans for Putin's visit were in doubt after a Russian news agency reported, quoting a single unnamed security source, that plotters were planning to assassinate Putin in Tehran.

Putin's visit to Iran, the first by a Kremlin leader since Josef Stalin went in 1943, has drawn intense interest because of Russia's role as a mediator in six-power talks designed to rein in Iran's nuclear ambitions.

The Kremlin leader said patience and negotiation were the best tools for dealing with Iran and said trying to intimidate Tehran was "hopeless".

"But to demonstrate patience and look for a way out is possible and should be done," Putin said. "If we have a chance to keep up these direct contacts, then we will do it, hoping for a positive, mutually advantageous result."

Merkel took a more hawkish line, saying that the United Nations must impose more sanctions on Iran if it does not comply with U.N. demands over its nuclear programme.


INTELLIGENCE REPORTS

Russia's Interfax news agency had reported on Sunday evening that Putin had been warned by his special services of a possible assassination plot during his visit to Tehran this week.

"A reliable source in one of the Russian special services, has received information from several sources outside Russia, that during the president of Russia's visit to Tehran an assassination attempt is being plotted," Interfax said.

Russian media are mostly controlled by the government and it would be unthinkable for a major Moscow news organisation to report an alleged plot against the president without prior official approval.

Russian secret services did receive intelligence about a plot against Putin, Russia's three main news agencies reported on Monday, quoting an unnamed security service official.

Russian television channels said previous plots to kill Putin had been foiled in Baku, Azerbaijan, in 2001 and in St Petersburg in 2000.

Iran dismissed the report as baseless, saying it was "psychological warfare" calculated by Tehran's enemies -- an apparent reference to Western powers -- to undermine Russian-Iranian relations.


'ASSASSINATION PLOT'

In a historical coincidence, reports of an assassination plot also hung over Stalin's 1943 visit to Tehran for a wartime conference with allies Winston Churchill and Franklin D. Roosevelt. On that occasion, Stalin said Soviet intelligence had uncovered Nazi plans to kill Roosevelt, persuading the American president to move into the Soviet embassy for his stay.

Putin's trip to Tehran was being watched closely by Western capitals anxious to curb an Iranian nuclear programme they fear masks a drive for an atomic bomb. Iran denies A-bomb ambitions and is building a nuclear reactor with Russian help.

Putin was officially travelling to Tehran to take part in a summit of Caspian Sea states.

But a planned private meeting with Iranian President Mahmoud Ahmadinejad could give him a chance to seek a peaceful compromise over Tehran's nuclear programme and to demonstrate his independence from Washington on Middle East issues.

Although Washington wants a tougher line on Iran and is much more suspicious of Tehran's nuclear objectives than Russia, the United States has repeatedly praised Moscow's cooperation at the six-power talks.

Putin has in turn promised during his visit to stick to the established six-party line on Iran -- to encourage Tehran to cooperate fully with International Atomic Energy Authority inspectors and show that its nuclear programme is intended only for peaceful purposes.