India’s billionaire Singh brothers , already embroiled in one international legal battle over alleged fraud, are being accused of "diversion, siphoning and digression of assets" by a New York-based investor in a lawsuit filed in the High Court of Delhi.The lending arm of Malvinder and Shivinder Singh’s publicly traded financial services firm Religare Enterprises Ltd., made 21 loans to a number of seemingly independent companies that routed at least $300 million back to privately held Singh firms on the same day, according to a central bank investigation of the company’s fiscal 2016 books filed as part of the 700-page suit in November.The suit, seen this month by Bloomberg News, alleges that the Singhs diverted the lender’s funds to aid them with a personal debt load of about $1.6 billion, which is forcing the sale of chunks of their empire that includes Religare and Fortis Healthcare Ltd., India’s second-largest hospital chain. A hearing in the case is scheduled for March 20.The allegations "are completely baseless and we categorically deny them," Religare said in an email response. "As the matter is sub judice we cannot offer more comments. However we will comment further at an appropriate time.”The plaintiff, a fund managed by $12.6 billion private equity firm Siguler Guff & Co. with a 6 percent stake in the Singhs’ small-business lending unit, Religare Finvest Ltd., asked the court to stop Finvest from lending more money to the Singhs and prevent its parent from selling assets. The halt aims to ensure Religare has the money to pay a potential liability to be pursued by the investor in arbitration, the suit says.The case pulls back the curtain on one of India’s highest profile corporate meltdowns, which erased nearly half a billion dollars of Religare’s market value, and sparked an exodus from its board.It also opens up another front for the Singhs, who are fighting to get out from under a personal debt load that’s already seen one default, while their attempts to sell assets are being blocked by another court battle: Daiichi Sankyo Co. of Japan’s attempts to enforce a $500 million award for alleged misrepresentations during the sale of another Singh company, Ranbaxy Laboratories Ltd., a decade ago. The Singhs are contesting the ruling.The Singh brothers "have been camouflaging the diversion of funds from RFL to meet their personal liabilities under the guise of legitimate business operations," the lawsuit alleges, using the acronym for Religare Finvest Ltd., adding that the diversion of funds has "the sole purpose of unjustly enriching" the brothers.The Singhs "are engaged in systematically plundering" Finvest, diminishing the ability of the parent company to honor its obligations, the suit alleges. Siguler Guff, which as an investor in the Resurgence PE Investments fund it manages owns part of the Finvest stake and represents the fund on Finvest’s board, says in the suit it is planning to seek arbitration to force the corporate parent to honor a provision in its original investment agreement to buy out its stake for about $43.5 million.A spokeswoman for Siguler Guff did not respond to an email seeking comment.Finvest’s loan book where the rerouting of funds was discovered has been under investigation by the Reserve Bank of India since at least 2015, according to the court documents filed as part of the suit. Interest on $283 million in loans still outstanding does not appear to be being paid, the suit alleges.A spokesman for the Reserve Bank of India didn’t reply to an email seeking comment.As of 1 p.m. on Monday, a day when Mumbai’s benchmark S&P BSE Sensex index rose to a record high, shares of Religare Enterprises declined 2.2 percent, while Fortis Healthcare fell 4.7 percent.The lawsuit further alleges that, despite telling the central bank that it would wind down its loan book, Finvest last year lent $76 million more to companies that are part of the Singhs’ group or identified in its corporate documents as "known" to them.Other instances of diversion alleged in the lawsuit are Finvest’s purchase from a third party of short-term debt issued by the Singh’s main holding company that has since been continually rolled over, and the deposit of about $118 million with a bank that allowed it to be used as security for money owed by the Singhs personally, essentially providing security for those obligations. On Jan. 5, the High Court ordered the bank deposit be left where it is, the documents show.The lawsuit alleges the Singhs were able to circumvent Finvest’s board on these transactions through a special committee they controlled that independently authorized loans and investments.The results of the central bank’s investigation and details of the case have not been previously made public.