Investors dumped more Adani stock on Monday as India's opposition staged protests calling for a full inquiry into allegations of major accounting fraud at the country's biggest conglomerate.

The group owned by tycoon Gautam Adani has lost around $120 billion in value since the claims were levelled by short-seller US investment group Hindenburg Research on January 24.

Trading in Adani Total Gas, in which French oil giant TotalEnergies owns a 37.4-percent stake, and in Adani Power was again suspended on Monday after the stocks fell five percent.

Shares in flagship Adani Enterprises, which before the rout had gained more than 1,000 percent in five years, closed 0.7 percent lower, having been off almost 10 percent in volatile early trade.

The slide has raised concerns about the group's ability to raise fresh financing to pay down its debts. It cancelled a share sale, and reportedly also a bond issue, last week.

Adani said Monday it was prepaying loans worth $1.1 billion, taken against shares for three of its companies, ahead of their maturity in September 2024. Analysts said the move was meant to reassure investors.

The announcement came as The Economic Times newspaper reported that Britain's Standard Chartered had joined Swiss banking giant Credit Suisse and Citigroup in the United States in halting the acceptance of Adani bonds as collateral for loans it advances to private banking clients.

The main opposition Congress party, which has called for a "serious investigation" into Adani's companies by the central bank and regulator, on Monday staged protests, including in New Delhi and Mumbai.

The party says that Gautam Adani's close ties with Prime Minister Narendra Modi, who is also from Gujarat state, allowed him to win contracts unfairly and to avoid proper oversight.

- Exposure fears -

"Don't you think there is something wrong here? We want to ask Modi's government: who gave banks the approval to provide a loan to Adani?" Khushboo Sharma from the youth wing of Congress told AFP at a protest in Delhi.

"The shares that have fallen, the loss that has been caused to the general public, who will pay for it?"

Analysts say Indian mutual funds and retail investors have minimal exposure to Adani shares, but institutional investors are more at risk.

Commerce Minister Piyush Goyal on Saturday defended Indian regulators, saying they were "very competent".

Finance Minister Nirmala Sitharaman on Sunday said that Adani had also won business in Indian states not run by Modi's governing Bharatiya Janata Party (BJP).

"Any project under Prime Minister Modi goes through the open tender process (of) global tendering," Sitharaman told broadcaster Times Now.

The company has rejected the claims made by Hindenburg and last week Adani, 60, insisted that the "fundamentals of our company are very strong, our balance sheet is healthy and assets robust".

His personal wealth has more than halved, seeing him fall from number three in the Forbes real-time list of the richest people in the world to 18th as of Monday, with a fortune of $60 billion, down from $127 billion.

India's securities regulator SEBI said Saturday that it was "committed to market integrity" and without naming Adani said it always properly examines all "specific entity related matters".