Tata Sons on Sunday renewed its appeal to shareholders of Tata group companies to remove Cyrus Mistry from their boards, saying that his presence as chairman "is likely to lead to fragmentation of the Tata Group".
An October boardroom coup ousted Mistry as chairman of Tata Sons, holding company of the $100 billion Tata empire, but he remains on the board of some group companies.
Patriarch Ratan Tata is back at the helm temporarily and a public power struggle has since ensued between the two sides.
The appeal by Tata Sons comes days ahead of key meetings at six group companies, including Tata Motors and Tata Consultancy Services , when shareholders are expected to vote on removing Mistry from their boards.
In a four-page letter, Tata Sons said that Mistry misled the selection committee set up in 2011 to select a chairman of Tata Sons to succeed Ratan Tata. The letter said Mistry had made lofty statements about his plans for Tata Group and that none of them had been implemented.
Tata Sons said at the time of appointment that Mistry agreed to distance himself from family enterprise Shapoorji Pallonji & Co but later retracted his position.
Mistry issued a statement on Sunday rejecting the accusations, saying that new engineering and construction contracts from the Tata Group to Shapoorji Pallonji dropped to nearly zero from a level of 11 billion rupees ($163 million) when he assumed office.
In the Tata Sons letter, the company said that Mistry has, over the past three to four years, concentrated power and authority as chairman in all major Tata operating companies and tried to weaken management structures in Tata companies "acting contrary to his fiduciary duties".
On Monday, Mistry defended his position to shareholders of six Tata group companies, explaining why he should not be removed as director at their shareholder meetings.
Tata Sons, in a statement on Wednesday, said that Mistry was removed as chairman because the board of Tata Sons had lost confidence in him and his ability to lead the group.
($1 = 67.4601 Indian rupees)
(Reporting by Rajendra Jadhav; Additional reporting by Promit Mukherjee; Editing by Dale Hudson and David Goodman)