Adani Group, India’s largest corporation and an aspiring media empire builder, has been accused by a U.S. investment firm of “pulling the largest con in corporate history.”

Hindenburg Research, a firm that engages in short-selling of company stocks in anticipation of a share price decline, Tuesday published a research document which said that the $218 billion Adani group was engaged in “brazen stock manipulation,” “accounting fraud” and money laundering.”

Adani Group denied the accusations. “The group has always been in compliance with all laws,” said chief financial officer, Jugeshinder Singh, in a statement on Wednesday.

The group’s founder, Gautam Adani, who is a close ally of Indian Prime Minister Narendra Modi, is calculated to be the richest person in Asia and the third or fourth richest person in the world, with a personal fortune of some $120 billion.

Adani Group is principally interested in sectors including port management, electric power generation and transmission, renewable energy, mining, airport operations, natural gas, food processing and infrastructure sectors.

Adani Group’s media interests are new and small in comparison with the rest of the conglomerate. In May last year, it bought a small digital publishing company. In August, Adani’s AMG Media Networks Limited (AMNL) mounted a hostile bid for New Delhi Television (NDTV), one of India’s most trusted news sources, and completed the 65% takeover in late December. The media businesses are not accused by Hindenburg of any misdeeds.

To qualify as the largest corporate con in history, the fraud would have to be bigger than the $60 billion Ponzi scheme at the private investment advisory business of respected Wall Street titan Bernie Madoff.

Hindenburg says it has researched Adani Group for two years and, similarly, finds Indian regulators failing to do their jobs or members of the media intimidated into silence. “Criticism of India’s elite businessmen and politicians has increasingly resulted in journalists being imprisoned or outright murdered. Stock market analysts have been arrested for writing negatively about companies. Amidst this climate of stifled expression, corporate fraud has largely gone unchecked,” it says. “Adani has pulled off this gargantuan feat with the help of enablers in government and a cottage industry of international companies that facilitate these activities.”

Among the specifics, Hindenburg accuses the group of: inflating revenue and profit figures; close family-control despite the size of the group; use of offshore companies in (Mauritius, Cyprus, the U.A.E., Singapore and The Caribbean) to disguise true ownership; and using Adani-controlled overseas funds to make the stock market listed entities appear more creditworthy than they really are. Hindenburg also catalogs several past investigations by Indian regulators into family members and associates for theft of taxpayer funds, corruption and a diamond trading scam.

Adani Group’s Singh, said that the company was shocked by the report, calling it a “malicious combination of selective misinformation and stale, baseless and discredited allegations.”

“The timing of the report’s publication clearly betrays a brazen, mala fide intention to undermine the Adani Group’s reputation with the principal objective of damaging the upcoming follow-on public offering from Adani Enterprises,” Singh said in a statement.