NEW DELHI: The heart of India's capital will transform into a sea of colourful mats Sunday as thousands perform the camel, cobra and other postures for the first International Yoga Day championed by Narendra Modi.

Shortly after dawn on a New Delhi boulevard, some 35,000 bureaucrats, students, soldiers and others are to take part in the 35-minute mass outdoor yoga session, hopeful of qualifying for the Guinness Book of Records.

Yoga enthusiasts in other countries are also expected to stretch and bend for Sunday's celebration of the ancient Indian practice, including in Britain where mats will be rolled out along the banks of the River Thames.

India's prime minister, a vegetarian who practices the craft daily, has made Yoga Day a key initiative of his Hindu nationalist government since he took office 13 months ago.

“Yoga has the power to bring the entire humankind together!” Modi tweeted last year after pitching the idea during his speech to the UN General Assembly.

Preparations in India have been gathering pace since the UN agreed to the day, with schools, military barracks and even jails encouraged to participate in their own sessions on Sunday.

Bollywood superstar Amitabh Bachchan and others have been roped in for promotion, and Modi's many potbellied officials ordered to classes to practice “wind-releasing” and other postures.

Posters and other advertisements have also been published throughout the country encouraging residents to descend on their local park for “yoga for harmony and peace”.

Modi calls yoga “the anchor of my life”, helping him work long hours on little sleep.

But the premier will make only a speech on Sunday and not take to the mat himself at the mass session along Rajpath boulevard.

Starting at 7:00 am (0130 GMT), instructors will teach the session, to be beamed on giant screens along the historic avenue.

Modi wants to reclaim yoga as an historical part of Indian culture which has been lost to the West because of its enormous popularity.

The premier, a staunch Hindu nationalist, has set up a ministry dedicated to promoting yoga, Ayurveda and other traditional Indian treatments. And he has started free yoga classes for his government's three million bureaucrats and their families.

“Yoga is the soft power of India and through that soft power the whole world can be one global village... (and) violence can be removed with this kind of peace,” Foreign Minister Sushma Swaraj has told reporters.

Swaraj will be at the UN's headquarters in New York for the day's launch when scores are expected to strike a pose in Times Square.

Against Islam

But the preparations have sparked criticism, mostly from religious minorities who accuse Modi's government of pushing a pro-Hindu agenda in officially secular India.

Some Muslim groups complained last week that chanting the sacred Hindu sound of “Om” during yoga as well as certain poses, such as “surya namaskar” or sun salutation, have clear Hindu overtones and were against Islam.

“While doing yoga, one needs to do surya namaskar, which means you pray to the sun. The government needs to understand Muslims cannot pray to anybody except Allah,” Asaduddin Owaisi, a Muslim lawmaker, told the Press Trust of India news agency.

Hardline Hindu lawmaker Yogi Adityanath, from Modi's right-wing Bharatiya Janata Party, has meanwhile said those objecting to yoga could drown themselves in the sea or leave India.

The government quickly distanced itself from his comments, reassuring critics that participation was optional and that the day was focused on improving health.

Scholars believe yoga dates back 5,000 years, based on archaeological evidence and references to yogic teachings in the ancient Hindu scriptures of the Vedas.

Experts like Ishwar Basavaraddi, head of the Delhi-based Morarji Desai National Institute of Yoga, described it as India's “best cultural export” that transcends religion and soothes hectic lifestyles.

“The foundation of yoga is science and philosophy, not any religion, “Basavaraddi told AFP, defining it as “holistic exercise through energy and mind management”.

Yoga novice Halil Ahmed, a paramilitary soldier in Delhi who has been taking part in government-sponsored classes, agreed.

“Yoga brings peace to the body and mind,” Ahmed told AFP after a recent session spent chanting “Om”.

“Yoga has benefited me in multiple ways.”