Why is yoga day stressing India?

Massive preparations are under way in India to celebrate the first International Day of Yoga on Sunday - even as an unsavoury row has broken out over whether practising the ancient discipline makes one a Hindu, writes the BBC's Geeta Pandey in Delhi.

At the International Sivananda Yoga ashram in south Delhi, a few dozen men and women are working to perfect their stretches, bends and breathing.

Guided by their teacher, with their palms flat on the mat, and knees pushing into their armpits, they slowly lift their entire bodies to rest on their arms.

They are performing Bakasana - also known as the Crow pose - which is among the toughest of yoga poses.

The 90-minute advanced class is for those who have been doing yoga for years and for whom it is a way of life.

Many Indians do yoga regularly to stay healthy

The 60-year-old ashram has played a crucial role over decades in popularising yoga in the West through its centres, and the "students" here are getting ready for Sunday's event.

"It is a good initiative. It will create further awareness about yoga the world over," says Prakash Chand Kapoor, senior yoga teacher and director of the centre.

Among the students is Anjali Singh. "Yoga is our gift to the world. I'm really proud we are celebrating this day," she says.

'Mindboggling numbers'

And India has made grand plans to ensure its success.

The lawns of India Gate in the heart of the capital are a hive of frenetic activity.

Rajpath - the King's Avenue - has been shut to traffic for days, dozens of metal detectors are in place, a massive public address system is being installed and 7,000 yoga mats are being unrolled.

A row has broken out with some Muslims saying yoga is against their religion

This is where 35,000 officials, soldiers and students are expected to perform 35 minutes of exercises, led by trained yoga teachers.

Prime Minister Narendra Modi, who is a huge yoga enthusiast and according to reports practices it daily, will be in attendance though he will not be doing yoga.

Similar events are being organised in hundreds of Indian cities and towns and across the globe too.

There will be yoga at Siachen, the highest battlefield in the world, and on high seas.

Popular yoga gurus with hundreds of thousands of followers, smaller private yoga studios and individuals have also pledged to participate in the event which the Indian government hopes will get into the Guinness Book of Records.

"The numbers are mindboggling, we expect tens of millions to participate," Foreign Minister Sushma Swaraj said.

Yoga teacher Aashish Nanda says the BJP government is politicising yoga

Ms Swaraj herself will be in New York where she will attend the celebrations with UN Secretary General Ban Ki-moon.

"Of the 193 member countries of the UN, yoga will be done in 192 countries - except in Yemen because of the conflict there," Ms Swaraj said.

'Damaging comments'

Yoga has been practiced in India for thousands of years, it's taught in many schools and individuals or groups can be seen doing asanas (yoga poses) in parks across the country.

Over the past few decades, it has also grown in popularity in the West where it has become a multibillion-dollar industry and been endorsed by celebrities like Madonna.

To popularise Sunday's event, top Bollywood actors and sports stars have been roped in and training camps are being held all over the country.

India says 192 countries are participating in Sunday's yoga day events

But the day, being billed as one to promote "harmony and peace", has hit a controversial note.

Some Muslim organisations say yoga is essentially a Hindu religious practise and that chanting "Om" or performing Surya Namaskar (Salutation to the Sun God) is against monotheism that Islam preaches.

Kamal Farooqui, a member of the Muslim Personal Law Board, told BBC Urdu that "yoga is not the only form of exercise, there are other forms of exercise too" and that by promoting yoga Mr Modi's Hindu nationalist Bharatiya Janata Party (BJP) was trying to push its Hindu agenda.

Angered by the debate, an MP from Mr Modi's party advised Muslims opposed to sun salutation to "go drown in the sea".

The government has been quick to point out that participation in the yoga day is not mandatory.

"We're not forcing any one to participate - there's no threat, no coercion," Ms Swaraj said, adding that Hindu chants or the sun salutation were not even part of the yoga day protocol and reports that Muslims were opposed to yoga were exaggerated.

But the slugfest has some yoga practitioners worried.

Yoga is believed to have originated 3,000 to 6,000 years ago

"This event was supposed to bring people together, but statements by senior BJP leaders are polarising people. These are damaging and unnecessary," said yoga teacher Aashish Nanda.

"Yoga is in a way Hindu because it comes from Gita and (Hindu god) Shiva was the first yogi. And the way the BJP is projecting it, there seems to be an agenda here," he adds.

Mr Kapoor of the Sivananda ashram agrees that yoga has its origins in Hinduism, but he believes that it is for everyone because it has "no caste, creed or religion".

"It's is not religion, it's a vast science of spirituality. The aim of yoga is to be a good human being. To be happy. So it's for everyone because everyone wants to be happy."

Irresponsible statements by politicians, he says, do not bother him.

"They're good for a panel discussion on TV. It's their job, and this - doing yoga - is my job," he says.

International Yoga Day in numbers:

• 35,000 officials, soldiers and students to participate in the main event on Rajpath in Delhi, PM Narendra Modi to attend

• Cost of Delhi event 300m rupees ($4.67m; £2.97m)

• 650 of India's 676 districts participating

• Of the 193 UN member countries, celebrations will be held in 192 countries - except in Yemen because of the conflict there

• Events being held in 251 cities in six continents

• 30,000 people to perform yoga at Times Square in New York