Men ride a motorbike as they come out of a past a Tata Motors car plant at Sanand in the western Indian state of Gujarat. Photo: Reuters/Amit Dave

Tata Sons’ interim chairman Ratan Tata branded his ousted predecessor Cyrus Mistry a “serious disruptive influence” on Wednesday.

The accusation was made in a letter sent to shareholders of six Tata Group companies days ahead of key meetings to vote on the removal of Mistry from their boards.

A bitter boardroom battle has been raging since an October coup ousted Mistry as chairman of Tata Sons, the holding firm of India’s largestconglomerate, and patriarch Ratan Tata returned to the helm temporarily. However, Mistry remains on the board of the six group companies, including Tata Motors and Tata Consultancy Services.

In his two-page letter, Ratan Tata said Mistry was removed as chairman because the board of Tata Sons had lost confidence in him and his ability to lead the group, and that his presence in group companies can make them “dysfunctional.”

He also said that several attempts at mediation went unheeded and that Mistry had also been offered an opportunity to step down voluntarily, which he rejected and was then removed.

Mistry’s office, in a statement, said the letter is “a combination of statements ranging from misrepresentation and convenient mischaracterisation”. It also denied claims of mediation attempts, saying Mistry was asked to step down only minutes before the board meeting in which he was ousted.