KOLKATA: Claiming that Netaji Subhas Chandra Bose did not die in a plane crash in 1945 but was killed at the instance of Soviet dictator Joseph Stalin, BJP leader Subramanian Swamy on Saturday demanded declassification of secret files on the leader.

Seeking declassification of files to unravel the mystery behind the legendary nationalist leader and freedom fighter's death, Swamy blamed Stalin of killing Bose in captivity in Siberia.

Participating in a Merchant Chamber of Commerce and Industry organized event here, Swamy, however, admitted that disclosing the secret files might jeopardize India's relation with Britain and Russia but assured of taking up the matter with Prime Minister Narendra Modi.

"According to the papers that exist with us, Bose had faked his death and escaped to Manchuria in China which was under Russian occupation, hoping Russia would look after him. But Stalin put him in a jail in Siberia. Somewhere around 1953, he hanged or suffocated Bose to death," said Swamy.

Swamy also claimed that the-then Indian Prime Minister Jawahar Lal Nehru was aware about Bose being held captive in Yakutsk Prison in Siberia.

"Declassification of Netaji documents in haste and without judging the consequences would be difficult. India's relations with Britain and Russia may be affected, but I will persuade the Prime Minister to disclose the documents," said Swamy.

"The mystery of Bose's disappearance must be solved and the files must be declassified. Because it was Bose's heroics that played a catalytic role in the British leaving India despite winning the world war," added Swamy.

A host of Netaji's descendants, enthusiasts and historians and organizations have been campaigning for declassification of secret files claimed to be in possession of various government departments.