Letters written by Subhash Chandra Bose's widow and daughter to the government are among the 29 classified documents, most of which relate to Netaji's disappearance, kept in the high-security vaults of the Prime Minister's Office.

Other confidential papers available with Prime Minister's Office include those relating to Netaji's ashes, Indian National Army treasure and policy papers about guidelines on posthumous conferment of Bharat Ratna Award.

These details form part of a list of PMO's 29 classified files on Netaji, that were released under the Right to Information law to Mission Netaji, a Delhi-based research trust.

The PMO had earlier refused to reveal the list of its classified documents on the grounds that divulging the titles and their contents could affect India's sovereignty and relations with foreign nations.

The matter, which was thereafter taken up with the Central Information Commission, directed the PMO on February eight to provide a list of 29 out of its 33 classified files along with their titles, after perusing through the list produced before it.

Four classified documents were, however, exempted from disclosure by Chief Information Commissioner Wajahat Habibullah, noting that it had references to foreign nations.

The Commission in its order noted that out of 29 files, seven were classified 'top secret', three 'confidential' while the rest were marked 'secret'.