Russian President Vladimir Putin and Chinese counterpart Xi Jinping discussed more than global affairs on the sidelines of the military parade in Beijing.

A live microphone captured the autocratic leaders discussing – through interpreters – ways of prolonging life, such as organ transplants and biotechnological innovations.

Putin and Xi have been in power for 25 and 13 years, respectively. Neither have suggested they’ll be leaving their top jobs any time soon.

The unguarded comments were captured by Chinese state media, and have been translated into English by the BBC.

“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,” Xi’s translator could be heard saying in Russian.

Following muffled remarks by Putin, his translator said: “With the development of biotechnology, human organs can be continuously transplanted, and people can live younger and younger, and even achieve immortality.”

The translator for Xi then says how there are predictions of living until 150 years old.

According to Russian state media, Putin later repeated his comments about extending life expectancy.

“Modern recovery methods, medical methods, even surgical ones dealing with the replacement of organs, enable humanity to hope for active life to last longer than it does today,” reports Tass.

“Average age is different in different countries but life expectancy will increase significantly”.

The huge parade yesterday was the first time Xi, Putin and North Korean dictator Kim Jung-Un have appeared together publicly. Some observers regard it as a direct message to western countries, which have steered away from them.

Among the 10,000 crowd watching the display of Chinese military might was former Victorian premier Daniel Andrews who shook hands with Xi Jinping before it started.