The crisis engulfing the Adani Group has intensified as hundreds of members of India’s opposition parties took to the streets to press for an investigation into allegations by a US short-seller against India’s second-biggest business group which triggered its market rout. The Adani Group said on Monday that its major investors, known in India as “promoters”, had pledged to prepay $1.1bn (£916m) in share-backed loans due for repayment by September 2024. The repayments include shares in Adani’s ports business, Adani Green Energy and Adani Transmission. Shares in Adani Port & Special Economic Zone jumped 9% after the announcement. Members of the opposition Congress party have been urging the prime minister, Narendra Modi, to order an investigation into the Adani Group companies after a US-based short-selling firm, Hindenburg Research, accused them of various fraudulent practices. The Adani Group has denied any wrongdoing. In Delhi, Congress party workers threw fake currency notes in the air and chanted slogans. Some burned a suitcase plastered with images of Modi and the Adani Group head, Gautam Adani. Some protesters scaled police barricades and were detained and taken away in police vans. Opposition party workers in the financial capital, Mumbai, and the southern city of Chennai gathered outside the offices of a state-run bank and the country’s largest insurer, which are known to have investments in Adani shares. So far, there is no sign the fracas is spreading across India’s financial sector and the protests are more a reflection of political theater rather than spontaneous public outrage. Lawmakers disrupted parliament for a third day on Monday as calls mounted for India’s market regulator to look into Hindenburg’s claims. Adani and his companies have lost tens of billions of dollars as investors dumped their shares. Last week, the group cancelled a $2.5bn share offering, promising to provide refunds to investors. The billionaire’s fortune had grown by more than 2,000% in recent years. Critics say he has benefited from strong relationships with Modi and his government, while others point out he also prospered under previous administrations. “What action has been taken, if ever, to investigate the serious allegations made over the years against the Adani Group?” Jairam Ramesh, the Congress party’s general secretary, said in a statement issued over the weekend. “Is there any hope of a fair and impartial investigation under you?” he said in a reference to Modi. Shares in Adani Enterprises, the group’s flagship, wobbled on Monday and were down 2.1% by mid-afternoon. Its market value has shrunk by more than 50% since the Hindenburg report. Stock in five other Adani listed companies fell by 5% to 10%. The move to repay share-backed borrowing early addressed one of the key concerns raised by Hindenburg: heavy borrowing using group shares as collateral. Adani said the pledge by major shareholders to repay that debt was “in continuation of promoters’ assurance to prepay all share-backed financing”. The wild swings in share prices have highlighted concerns over corporate governance, especially as the country tries to woo foreign investors. On Saturday, the Securities and Exchange Board of India (SEBI) issued a rare statement seeking to calm investors. “During the past week, unusual price movement in the stocks of a business conglomerate has been observed,” the market regulator said, without naming the Adani Group. It said mechanisms were in place to deal with volatility in specific stocks. The SEBI would examine any information before taking appropriate action, it said. On Friday, the finance minister Nirmala Sitharaman dismissed concerns that the controversy would alarm global investors, saying India’s financial markets were “very well regulated”. Adani built a fortune in trading and in coal mining and then branched into construction, power generation, operation of ports and airports, manufacturing defence equipment and running a media company. Before the latest troubles, Bloomberg’s billionaire index listed Adani as Asia’s richest person and the world’s third wealthiest. Bloomberg’s rankings now put him at 21st wealthiest after his net worth sank to $59bn from $120bn.