Corporate lobbyist and public relations professional Nira Radia had alleged links with foreign intelligence agencies, prompting the government to authorise the income tax department to tap her phone conversations.
The government's affidavit submitted in the Supreme Court is reported to have details of Radia's alleged anti-national activities.
The government submitted the affidavit in response to the issues raised by Tata Group chairman Ratan Tata in his petition relating to the leak of the Radia tapes.
The finance ministry had, as far back as on 16 November 2007, asked the income tax department to tap Radia's conversation after it noticed that she had earned nearly Rs900 crore in just three years, media reports said.
The government's affidavit cited the letter to show that she was in touch with other countries' intelligence agencies and might have been involved in anti-national activities.
The government, however, said it was not responsible for the leak of the conversations, but assured the court to prevent any further leak of such conversations.
According to the affidavit, the "secrecy and security (of the taped conversations) have been maintained and the integrity and safety of the data in electronic form have been ensured through proper checks in the system through which the recordings have taken place".