Millions across India on Tuesday celebrated the International Day of Yoga, the country's signature cultural export, with Prime Minister Narendra Modi joining 30,000 participants in a mass session of exercise and meditation.

Modi pushed for the annual event to be celebrated worldwide soon after winning power in 2014, lending his political weight to an industry that has grown up around the ancient physical and spiritual discipline and is estimated to be worth $80 billion.

The 65-year-old premier, who is reputed to rise at dawn to do yoga exercises before starting work, joined school children, residents and government employees in the northern city of Chandigarh for an early-morning mass yoga session.

"With zero budget, yoga provides health assurance and it does not discriminate between rich and poor," Modi said in his speech before the session.

He also called for a focus on mitigating diabetes through yoga. The number of adults with diabetes has quadrupled worldwide in less than four decades to 422 million, and the condition is fast becoming a major problem in poorer countries, a World Health Organization study showed in April.

Yoga guru Baba Ramdev and spiritual gurus Sri Sri Ravishankar and Sadhguru Jaggi Vasudev all supported the yoga initiative, with several events.

Modi's ministers joined in at sessions across India, with several of them posting tweets and pictures.

"Extremely happy to be amongst you all to participate and practice yoga," tweeted Urban Development and Housing Minister Vekaiah Naidu.

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Hundreds of thousands gathered at spots across New Delhi to join in the government-organized mass yoga sessions in parks and on Rajpath, a central avenue.

Last year, the Indian capital set a world record for the largest yoga demonstration at a single site.

"I like the idea of yoga becoming the norm in our homes. Seems like fun, and with phenomenal consequences," Tarot card reader Ruchira Mittal tweeted on social media.