Former Tata Sons chairman Cyrus Mistry has written a letter to six group companies to lay out the case for why he should not be ousted as director, Reuters reported on Monday. In the letter, Mistry criticised the Tata “high command”, while defending his position and work as chairperson. He also pointed out the need for reforms at Tata Sons and group companies, the news agency reported.

“At the heart of the sustainability [of] the Tata Group is governance reform, throughout in the institution,” the letter said, according to The Economic Times. “This would mean the Government ensuring the working of Tata Trusts, which are public charitable structure[s],” it said.

The letter – written to Tata Steel, Tata Motors, Tata Chemicals, Tata Power, Tata Consultancy Services and Indian Hotels – added that the “conferment of all decision-making power in one man or a “high command” was unethical. “It is critical that serious decisions of severe magnitude and consequence are not taken whimsically, without much thought, or for unstated collateral objectives,” the communication said. A method of checks and balances was needed to run the firms, Mistry said.

The letter comes ahead of shareholder meetings of Tata group companies called by Tata Sons as part of its attempt to remove the former chairman from his position. Mistry was ousted as chairperson on October 24.

The Tata Group has accused Mistry of being responsible for its dwindling revenue, but Mistry has dismissed the group’s allegations against him. In a letter to his employees, interim chairperson Ratan Tata had said the decision to sack Mistry was “absolutely necessary” for the group’s success.