Tata Sons on Tuesday filed a legal notice against its former chairperson Cyrus Mistry for allegedly breaching confidentiality. It accused the former chief of the conglomerate of making sensitive and confidential documents public, PTI reported.

The notice was sent to Cyrus Investments and Sterling Investments, firms controlled by Mistry’s family that had sued the holding company on December 20. It claims that their petition in the National Company Law Tribunal had contained “confidential data, business strategies and financial information” related to the affairs of Tata Sons, and that this “reckless” move has caused irreparable loss to the conglomerate, The Economic Times reported.

In their petition, the two investment firms had accused Tata Sons of bad practices, oppression and mismanagement. The Mumbai court has directed the companies to submit documented proof of the allegations they made against Tata Sons.

On December 19, Mistry had decided to resign from all Tata Group companies saying it was time to shift gears and “be more incisive in securing the best interest of the Tata Group”. He had said that Ratan Tata staged “an illegal coup” on October 24, the day he was sacked from his post in the company.

Mistry has been in a widely publicised battle with the Tata camp since he was stripped of his chairmanship. Since then, he has been removed from the board of directors from a number of operating companies under the Tata Group, including Tata Steel, Tata Industries, Tata Consultancy Services and Tata Teleservices.

Shareholders had also voted to remove independent director Nusli Wadia from the board of Tata Steel and Tata Chemicals, after he expressed support for Mistry. Wadia had filed a defamation case against Tata Sons and Ratan Tata for making “false and baseless innuendos and allegations” against him that caused “distress, hurt and humiliation”.