In his letter to Sebi dated July 8, Mr Gangwal sought the market regulator's intervention, in a move that suggested that a previously reported row between the estranged co-founders was escalating. The market regulator asked the company to respond to the letter by July 19, according to a regulatory filing by InterGlobe Aviation on Tuesday.

Even a "paan ki dukaan" (betel shop) would have managed matters "with more grace", Mr Gangwal wrote while referring to various events at the company, Mr Gangwal wrote in his letter, copied to Prime Minister Narendra Modi and Finance Minister Nirmala Sitharaman besides other ministers and bureaucrats.

InterGlobe shares nosedived to their lowest intraday level recorded since March in today's session before closing 11.13 per cent or Rs 174.30 lower at Rs 1,392 on the NSE. (Check IndiGo share price here)

CEO Mr Dutta told the company's employees that the issues between promoters have nothing to do with airline and its functioning. (Also read: Rakesh Gangwal has no plans of taking control of IndiGo, says CEO)

Reports of the alleged conflict between Mr Gangwal and Mr Bhatia first emerged in May this year, which were denied by the airline.

Mr Gangwal accused Mr Bhatia and his firms of indulging in questionable related-party transactions (RPTs), and proposed an extraordinary general meeting with shareholders. In a statement late on Wednesday, Rahul Bhatia's InterGlobe Enterprises (IGE) said that all transactions with the company have been executed on an arms' length basis in the ordinary course of business.

The matter relates to a spat between the co-founders over payment of rent for the airline's headquarters owned by Mr Bhatia's InterGlobe Enterprises, and crew staying at hotels where InterGlobe Enterprises has a stake.

Mr Gangwal has alleged that over the years, Mr Bhatia began building "an ecosystem of other companies that would enter into dozens of related party transactions" with the airline. "We are not against RPTs as long as proper checks and balances exist and such RPTs are in the best interest of the Company," Mr Gangwal wrote in his letter.

InterGlobe Enterprises further said that the group has "nurtured and supported" InterGlobe Aviation through its "formative and expansion years by making available these services".