BEIJING, Sept 4, 2025 (BSS/AFP) - Chinese President Xi Jinping and Russia's Vladimir Putin discussed life-prolonging organ transplants and immortality as they chatted before Beijing's massive military parade this week, in comments picked up by state media microphones.

Historic images showed Xi shaking hands and speaking with Putin and North Korean leader Kim Jong Un as they walked down a red carpet by Tiananmen Square, in scenes viewed as a challenge to US President Donald Trump.

"These days... 70 years old," Xi said in Mandarin as he walked beside Putin and Kim, footage from state broadcaster CCTV showed.

Xi's translator, conveying his remarks to Putin, is then heard in Russian quoting a line from a Tang dynasty poem: "In the past, it used to be rare for someone to be older than 70 and these days they say that at 70 one's still a child."

Putin then turned towards Xi, speaking while gesturing with his hands, though this is inaudible on the CCTV feed.

The same Chinese translator then relayed Putin's remarks to Xi.

"With the... development of biotechnology, human organs can be continuously transplanted, people could get younger as they grow older, and may even become immortal," Putin said, according to the translator.

Xi then spoke again in Mandarin as the camera cut away: "Predictions are, in this century, it may be... possible to live to 150 years old."

Putin confirmed the exchange during a press briefing on Wednesday.

"Ah, I think it was when we were going to the parade that the Chairman spoke about this," he told reporters, referring to Xi.

"Modern means -- both health improvement and medical means, and then even all kinds of surgical ones related to organ replacement -- allow humanity to hope that active life will continue not as it does today," Putin added.

The Chinese and Russian leaders, both 72, have not expressed any intention of stepping down.

While Xi's predecessors Jiang Zemin and Hu Jintao relinquished power after 10 years in office, he abolished term limits in 2018 and in 2023 was handed a third term as Chinese president.