Indian opposition demands market regulator quit over 'compromised' Adani probe

India's opposition has called on the chief markets regulator to resign after US-based short-seller Hindenburg Research claimed past investments compromised an investigation into the Adani Group.

The Adani Group, a sprawling ports-to-power Indian conglomerate, saw $150 billion wiped from its market value last year after a bombshell report by Hindenburg accused it of "brazen" corporate fraud.

India's top court asked the Securities and Exchange Board of India (Sebi) to investigate the allegations.

Hindenburg then accused Sebi chairperson Madhabi Puri Buch and her husband on Saturday of having held investments in offshore funds a senior Adani family member also allegedly used.

Buch has rejected the allegations as "baseless" and the Adani Group has called Hindenburg's latest claims "malicious, mischievous and manipulative".

However, opposition Congress party leader Rahul Gandhi said the securities regulator had been "gravely compromised" and called for her resignation, as well as a joint parliamentary investigation.

"The integrity of Sebi, the securities regulator entrusted with safeguarding the wealth of small retail investors, has been gravely compromised by the allegations," Gandhi said in a statement on Sunday.

"Honest investors across the country have pressing questions for the government: Why hasn't Sebi chairperson Madhabi Puri Buch resigned yet?" he said.

Gautam Adani, the family-run conglomerate's founder and the world's 12th richest person according to a Bloomberg index of the world's billionaires, denied Hindenburg's original allegations and called its report a "deliberate attempt" to damage its image for the benefit of short-sellers.

The forensic financial research firm also claimed that Vinod Adani, Gautam's elder brother, "manages a vast labyrinth of offshore shell entities" in tax havens including Mauritius, Cyprus and several Caribbean islands.

Hindenburg, citing whistleblower documents, has now also accused Buch and her husband of having held investments in offshore funds that Vinod Adani also allegedly used.