Mumbai: The power struggle in the Tata Trusts - the nonprofit and philanthropic group that collectively owns about 66 per cent of Tata Sons - seemed set to explode on Tuesday after Noel Tata, Venu Srinivasan, and Vijay Singh reportedly voted against extending Mehli Mistry's trusteeship.

Mistry joined the board last week in voting to approve Srinivasan's life trusteeship and may have been expecting that favour to be returned, despite reportedly leading a challenge. Sources said he may now pursue legal options. A resolution passed last year granted existing trustees a life term. The resolution said: "... on the expiry of tenure of any trustee, that trustee will be re-appointed... without any limit being attached to period of tenure... in accordance with the law".

However, sources said that trusteeship renewals "are required to be unanimous, per past practice... (but) renewal for life requires unanimous approval", suggesting Mistry's appointment as a trustee-for-life needed an active sign-off from other board members.

If the vote to remove Mistry stands, he will be ejected from the board, potentially ending a rift that many business analysts felt could undermine the stability of the Tata Group, a corporate behemoth whose listed entities have an estimated total market capitalisation of Rs 25 lakh crore.

That rift could impact strategic decisions at Tata Sons, which is the Tata Group's principal holding company, and emerged at a September 11 board meet to consider the reappointment of ex-Defence Secretary Vijay Singh as a nominee-director to the former's board.