The Kremlin started coming up with an evacuation plan for Putin in the spring, a former aide said.
It involves fleeing to Venezuela or Argentina, ex-speechwriter Abbas Gallyamov said.
Putin first considered a plan to evacuate to China - but later rejected the idea, Gallyamov said.
Russian President Vladimir Putin has a plan to flee to exile in South America if he loses the war in Ukraine, a former aide said on Tuesday.
The Kremlin began working on a backup plan, unofficially dubbed "Noah's Ark", in the spring said Abbas Gallyamov, a political consultant and ex-speechwriter to Putin, in a Telegram post.
Gallyamov cited unnamed insiders for his information. He has not worked for Putin since 2010 and is himself living in exile from Russia. He framed the evacuation as an extreme contingency plan.
Analysts do not generally anticipate Putin being forced from power, despite the heavy setbacks in the Ukraine invasion.
Former Western diplomats and government officials told Reuters in October that his grip on power remained firm. US officials in May told CNN that there was no immediate prospect of Putin being ousted.
The emergency plan involves "finding new lands where you can go if the homeland becomes completely uncomfortable," Gallyamov said.
"The leader's entourage does not exclude that he will lose the war, lose power and he will have to urgently evacuate somewhere," he added.
He also said that Putin first considered a plan to evacuate to China - but later rejected the idea on the basis that the chances of "cooperation" from the Chinese would most likely be slim.
"The Chinese are too self-conscious and too contemptuous of others - especially losers. Hope, as it has now become clear, is not enough for them," he wrote.
Argentina and Venezuela are now among the top two options for Putin to flee to, Gallyamov said, adding that Russian oligarch Igor Sechin has a good relationship with authoritarian Venezuelan President Nicolás Maduro.
Sechin, who is Putin's right-hand man, has been put in charge of the evacuation plan, Gallyamov said.
Insider was unable to independently verify these claims.
Gallyamov first worked in Putin's speech-writing team from 2000 to 2001, and then from 2008 to 2010. He has been living in exile in Israel since 2018.
He has regularly commented on the state of the war in Ukraine since the start of Russia's invasion on February 24.
Gallyamov's comments come amid ongoing reports that Moscow's forces continue to suffer battlefield defeats and lose territory to Ukrainian troops.
In a televised address on Wednesday, Putin admitted that it could be a very long war and also warned that the risk of nuclear war was growing.