Shares of Interglobe Aviation Ltd fell as much as 19 per cent on Wednesday after one of the co-founders of India's largest airline IndiGo alleged violation of corporate governance rules at the parent group. Interglobe shares hit their lowest since March and were on course for their worst day since January 2016.

At 9.55 am, the stocks of InterGlobe Aviation were trading 12.61 per cent lower at ₹1,368.25.

IndiGo co-founder Rakesh Gangwal on Tuesday also asked the country's securities regulator to intervene in the matter, a move that suggests that a previously reported row between Gangwal and fellow co-founder Rahul Bhatia was escalating.

“I have vigorously attempted for almost a year to persuade the company to shore up its governance standards, and all my attempts have been thwarted by the IGE Group,” Gangwal said in Tuesday's letter to the Securities and Exchange Board of India, referring to Bhatia's affiliate group. Gangwal and Bhatia each own less than 40 per cent in Interglobe, giving both co-founders a major say in its strategy and plans.

Rakesh Gangwal, one of the airline's founders, alleges violation of corporate governance rules at Interglobe in a letter to markets regulator the Securities and Exchange Board of India. “I have vigorously attempted for almost a year to persuade the company to shore up its governance standards, and all my attempts have been thwarted by the IGE Group,” Gangwal said. IGE is an affiliate of IndiGo's other co-founder Rahul Bhatia.

Interglobe has risen 34 per cent this year, thanks partly to the decline of cash-strapped competitor Jet Airways, after which IndiGo and other airlines raced to take Jet's coveted slots at airports. Meanwhile, shares of IndiGo's rival SpiceJet are up 8.74 per cent at ₹127.50.