NEW DELHI, March 9 (Reuters) - Indian environmentalists are aghast at the hosting of a huge cultural festival on the floodplain of Delhi's main river that begins on Friday, warning that the event and its 3.5 million visitors will devastate the area's biodiversity.
The "World Culture Festival", organised by one of India's best-known spiritual gurus, Sri Sri Ravi Shankar, spreads across 1,000 acres (400 hectares) on the banks of the Yamuna. It features a 7-acre stage for 35,000 musicians and dancers, newly built dirt tracks and 650 portable toilets.
Green groups accuse organisers of ripping up vegetation and ruining the river's fragile ecosystem by damaging its bed and disrupting water flows. They want authorities to cancel the event before more harm is done.
"This land is not meant for any of those things. The biodiversity of the land has been completely destroyed," said Anand Arya, one of several environmentalists who petitioned India's top green court.
"Where will the sewage and the excrement go? All across the floodplains!" he said, adding that the waste left by visitors would endanger a nearby bird sanctuary.
Prime Minister Narendra Modi, who like Ravi Shankar is a yoga devotee, was due to attend Friday's opening, but it is not clear whether he will do so after the event sparked such uproar - and not just among environmentalists.
Delhi police have warned of "utter chaos" at the event unless safety lapses are addressed, the Indian Express reported on Wednesday, citing a March 1 letter to the federal government that says the stage lacks a structural stability certificate.
Ravi Shankar, who enjoys a cult following in India and abroad, has rejected the criticism. He has said he should be rewarded for hosting the event alongside one of the country's most polluted rivers.
His organisation's lawyer, Saraswati Akshama Nath, said necessary approvals including safety certificates were granted in December before construction began, and that the structures would be removed once the three-day festival ends.
"Consent was given to us by all the authorities," she told Reuters outside the court on Tuesday. "We have only used eco-friendly material."
The National Green Tribunal has recommended Ravi Shankar's Art of Living Foundation be fined 1.2 billion rupees ($18 million) to restore the land, and is expected to make its final ruling on Wednesday.
Meanwhile, back at the festival site, builders are rushing to finish what they say is the world's biggest ever performing stage.
"This here will have a symphony of 8,500, and this 20,000 performers on stage at any one time," said Prasana Prabhu, a trustee of Ravi Shankar's foundation. (Reporting by Tommy Wilkes; Editing by Douglas Busvine, Robert Birsel)