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Indian Prime Minister Narendra Modi (C) performs yoga during a mass yoga event on the International Yoga Day in Dehradun, India, on June 21, 2018. The UN declared June 21 as International Yoga Day in 2014. (Xinhua)

NEW DELHI, June 21 (Xinhua) -- India celebrated the International Day of Yoga on Thursday, officials said.

The main event of Yoga celebration was organized in Dehradun, the capital city of northern state of Uttarakhand.

India Prime Minister Narendra Modi led thousands of people in performing Yoga at the Forest Research Institute in Dehradun on Thursday.

Modi called upon people to make Yoga a movement and part of their lives.

"Yoga has emerged as the biggest unifying force in the world and has become a biggest mass movement," Modi said in his address.

Various ministers led the Yoga sessions in different cities across India to mark the day, officials said.

Yoga includes stretching and bending of body besides doing breathing exercises aimed at transforming body and mind. Proponents of the exercise say it is a 5,000-year-old physical, mental and spiritual practice with origins in India.

The United Nations declared June 21 as the International Day of Yoga after Modi, a Yoga enthusiast, lobbied for the ancient Indian art.