Man vs Wild: PM Modi and Bear Grylls crossed a freezing river in a makeshift boat.

Prime Minister Narendra Modi hit television screens like never before on Monday, talking about his life and the environment -- and smelling elephant dung -- with Bear Grylls.

The Discovery Channel programme "Man Vs. Wild" saw PM Modi seek to burnish his credentials as a protector of nature, telling his story to the British television adventurer in a rainy nature reserve.

"Every plant is a flower. We see God in every plant," PM Modi said as the two men made a spear and crossed a freezing river in a makeshift boat.

"It is every human's responsibility (to protect the environment). The biggest problem is our lifestyle. We exploit nature for our enjoyment, and that is the biggest problem," he said in Hindi, with Grylls appearing to understand.

PM Modi, re-elected earlier this year, also told Grylls about his humble beginnings as a tea-seller's son and his solo trips of spiritual awakening into the Himalayas in his youth.

The programme, widely advertised in the media, ended with a gushing Grylls saying a prayer for India and for PM Modi, whom he called an "iconic global leader".

PM Modi, 68, has published videos of himself doing yoga and at the end of this year's election campaign was shown on television meditating in a remote holy cave.

During the election campaign, which ended in a thumping victory, PM Modi portrayed himself as the humble but determined "watchman" protecting India from its enemies within and without.

He told his Twitter followers earlier Monday that his adventures with Grylls, 45, would "throw light on environmental conservation and climate change."

India is home to 22 of the world's 30 most polluted cities, according to Greenpeace, and some of the planet's dirtiest waterways.

Poisonous air killed 1.24 million Indians in 2017, according to a study published last year by The Lancet Planetary Health, which said tens of millions of people face serious health risks.

India currently generates about two-thirds of its electricity with coal and gas, making it the world's third-biggest emitter of greenhouse gases.