“I would like to thank you for coming despite all the obstacles,” Mr Putin told the actor, who was attending the summit on tigers in St Petersburg.

“A person with less stable nerves could have decided against coming, could have read it as a sign – that it was not worth going,” Mr Putin said.

The Russian prime minister, who is hosting the summit, said the Titanic star had “literally tore his way through to Saint Petersburg,” calling him “a real man” (or “muzhik”) for his persistence.

DiCaprio then called himself half-Russian, after disclosing that two of his late grandparents were Russian, the state-run RIA Novosti news agency reported.

“Well, you will get to know Saint Petersburg tomorrow and grow proud of your Russian roots,” Mr Putin replied.

DiCaprio was among the passengers on a Delta Airline jet that was forced to make an emergency landing in New York on Monday after losing an engine.

His second plane faced strong headwinds and was required to make an unscheduled refuelling stop in Helsinki, Mr Putin told the audience.

Mr Putin has carefully cultivated a tough-guy image throughout his political career, using strong language in speeches and practicing judo and even co-piloting fighter jets in front of the television cameras.