Mumbai, Dec 19 (PTI): After a bitter eight-week boardroom battle against Ratan Tata's "illegal coup", ousted Tata Group Chairman Cyrus P Mistry today quit from the boards of six listed companies including Tata Motors and Indian Hotels and vowed to shift his fight to a "larger platform".

In a two-page statement and a recorded video message, Mistry, who was unceremoniously removed as Chairman of Tata Sons on October 24, said the objective of effective reform and best interests of employees, shareholders and other stakeholders of the Tata Group "would be better served by moving away from the forum of the extraordinary general meetings".

While Mistry, 48, did not specifically say he was resigning from either Tata Sons, where he still continues as a director despite being removed as chairman, or from the operating firms, sources close to him said he has quit.

Both sides told the media that operating companies will make regulatory announcements to the stock exchanges shortly.

Tata Sons, the holding company of the USD 103 billion group, has called extraordinary general meeting (EGMs) of listed companies to consider its proposal to remove Mistry as director on their board.