Indian billionaire Gautam Adani has been indicted by US prosecutors for his alleged role in a $US265 million ($407 million) bribery scheme, plunging his industrial conglomerate Adani Group deep into crisis and causing share prices to tumble.
Arrest warrants have been issued for Mr Adani and his nephew Sagar Adani and prosecutors plan to hand those warrants to foreign law enforcement officials, according to court records.
Mr Adani is now one of the few billionaires formally accused in the US of criminal wrongdoing.
So, just how powerful is Gautam Adani? And why has he been charged?
Who is Gautam Adani?
The businessman is one of the world's most wealthy people.
He's worth $US69.8 billion ($107.1 billion), according to Forbes magazine, making him India's second-richest man.
Born to a middle-class family in Ahmedabad, Gujarat, he dropped out of school at 16 and moved to Mumbai to find work in the gem trade.
After a short stint in his brother's plastics business, he launched the flagship family conglomerate that bears his name in 1988.
He built his fortune in the coal business, with the Adani Group later growing to involve many aspects of Indian life: from making defence equipment, to building roads and selling cooking oil.
In recent years, the company has also made moves into renewable energy.
Mr Adani, 62, differs from his peers among India's mega-rich, many of whom are known for throwing lavish birthday and wedding celebrations that are later splashed across newspaper gossip pages.
A self-described introvert, he keeps a low profile and rarely speaks to the media, often sending lieutenants to front corporate events.
"I'm not a social person that wants to go to parties," he told the Financial Times in a 2013 interview.
Why has he been charged?
The indictment in New York accuses Adani Group's leadership of paying more than $US265 million ($407 million) to Indian government officials to secure lucrative contracts worth more than $US2 billion ($3 billion).
It further charges Mr Adani and seven other officials with lying about the bribery in order to raise capital from international investors, including those in the United States.
Supporters of India's main opposition Congress party protest in New Delhi after Mr Adani's indictment. (Reuters: Anushree Fadnavis)
The indictment accuses Mr Adani of personally meeting with an Indian government official to "advance" the bribery scheme, and of meeting with other defendants to "discuss aspects of its execution".
In a statement, the conglomerate denied the charges, calling them "baseless", and said they were seeking "all possible" legal recourse.
How powerful is Gautam Adani?
Gautum Adani wields significant power and influence — both in India and globally — according to Griffith University professor Ian Hall.
Mr Adani is considered a close associate of Indian Prime Minister Narendra Modi. (AFP: Dibyangshu Sarkar/File)
"India's economy is dominated by these big groups, and Adani Group has emerged as one of the largest and most successful over the last 10 years," the veteran India analyst told the ABC.
"He wields an increasing amount of influence more broadly because of some of the projects that he's involved in.
"Projects like like the ports and shipping businesses are strategically important, in themselves, but also in an era where there's competition going on between China and the United States and other players over things like supply chains.
"To have an actor like Adani in that particular space makes him politically important, even beyond the connections that he has with the Indian government."
How close is he to India's prime minister, Narendra Modi?
Mr Adani is considered a close associate of Prime Minister Narendra Modi, even offering the leader the use of a private company jet during the 2014 election campaign that swept him to power.
After being purchased by Mr Adani, leading Indian media outlet NDTV is considered pro-Modi and pro-government. (Reuters: Adnan Abidi)
Opposition parties and other critics have long claimed their relationship helped him to unfairly win business and avoid proper oversight.
He's still very close to Mr Modi, according to Professor Hall, after initially establishing a relationship when the Indian prime minister was the chief minister of Gujarat.
"They worked together so that he could assist the BJP [Bharatiya Janata Party] in Modi's campaigns and finance some of that," he said.
"And in return, if you like, he got all the things that go with being close to politicians: access to information, sometimes access to things like loans, and so on."
Adani Group has business interests in most facets of Indian life: from making defence equipment to building roads and selling cooking oil. (Reuters: Amit Dave)
Mr Adani also owns several media businesses, such as New Delhi Television (NDTV), which shifted strongly to support the Modi government following its takeover. The network was previously considered one of the few media outlets willing to criticise Mr Modi.
"His media outlets are very pro-government, pro-Modi, pro-BJP," Professor Hall said.
How will Modi's government respond?
Narendra Modi's government has yet to comment on the charges but a spokesman for his ruling party, Amit Malviya, said the indictment appeared to implicate opposition parties rather than his own.
"Don't get needlessly excited," Mr Malviya wrote on social media.
UNSW Associate Professor Mark Humphery-Jenner, an expert in corporate finance and law, says the charges pose a unique political challenge for Narendra Modi.
"In almost any other circumstance, if someone is alleged to have engaged in wide-scale bribery, and alleged to have engaged in widespread securities fraud, that should be a relatively standard case where you could extradite them," he told The World.
"However, because Gautam Adani is so close to Narendra Modi … it's certainly going to be a diplomatic headache."
What are Adani's interests in Australia?
The Adani Group's Australian subsidiary, Bravus, owns Central Queensland's Carmichael coalmine, one of the most contentious mining projects in Australian history.
Stop Adani signs held by environmental activists at a protest in Sydney in 2018. (AAP: Joel Carrett)
Since its approval a decade ago, it has generated strong community opposition over impacts on the Great Barrier Reef and groundwater, and its carbon emissions.
It sparked years of "Stop Adani" protests from concerned environmental activists.
Bravus also owns and operates the North Queensland Export Terminal near Bowen, and the Rugby Run solar farm near Moranbah.
Then-Queensland premier Annastacia Palaszczuk with Gautam Adani in 2016. (AAP)
Has Adani Group faced scrutiny before?
Last year, a bombshell report from US investment firm Hindenburg Research claimed Adani Group had engaged in a "brazen stock manipulation and accounting fraud scheme over the course of decades".
Hindenburg said a pattern of "government leniency towards the group" stretching back decades had left investors, journalists, citizens and politicians unwilling to challenge its conduct "for fear of reprisal".
The US firm is known as a short-seller, a term for Wall Street traders that bet that prices of certain stocks will fall, and it had made such investments in relation to Adani Group.
The conglomerate denied wrongdoing and characterised the report as a "calculated attack on India" but lost $150 billion in market capitalisation in the weeks after the report's release.
Mr Adani saw his own net worth plunge by $60 billion over the same period.
But Professor Hall said that after the Hindenburg accusations were denied Adani Group had been able to move on.
"Post-Hindenburg and post-election, they bounce back because [Mr Adani] has proved to be able to make shareholder value and make profit.
"There's no shortage of investors within India and outside that would be willing to back his business."
How will India react to the charges?
Like the Hindenburg claims, the fraud allegations will cause controversy and scandal in India, according to Professor Hall.
"It will be met with lots of nodded heads amongst those who believe that Adani is up to no good," he said.
"There will be lots of people, though, who will be deeply offended, and will suggest that the United States is trying to slow India's rise or have a go at the Modi government."
Opposition figure Rahul Gandhi says the prime minister will protect Mr Adani from charges in the US. (Reuters: Priyanshu Singh)
None of the multiple defendants in the case, including Mr Adani, are in custody, but India's opposition Congress Party leader Rahul Gandhi said the businessman should now be arrested.
"We demand that Adani be immediately arrested," Mr Gandhi told reporters in New Delhi.
"But we know that won't happen as Modi is protecting him.
"Modi can't act even if he wants to, because he is controlled by Adani," the politician said.
Could Donald Trump's presidency change things?
According to Professor Hall, one aspect of the scandal that's been largely overlooked is the effect on bilateral relations between the US and India, which at the moment are strained due to an alleged murder plot of a Sikh separatist on US soil.
Another related dimension is the upcoming presidency of Donald Trump, which could impact Mr Adani's charges, Professor Hall said.
Mr Adani is one of the world's most wealthy people. (Reuters: Amit Dave/File)
He said it remained to be seen whether Mr Trump would pressure the US Department of Justice to drop the charges against Mr Adani, and other charges related to former Indian intelligence officials.
"There's definitely a hope in Delhi that some of these charges could be made to to go away, potentially, because of the political relationship between Modi and Trump.
"And that that's a proposition that's yet to be tested."
ABC/wires