"We demand the immediate declassification of this CBI file to set the historical facts right. The people of India would like to know who passed on information to British intelligence for which Sarat Chandra Bose, Subhas Bose's elder brother, went to jail," the family said in a press release here.
Chaudhuri, best known for 'The Autobiography of an Unknown Indian', was the secretary of Sarat Chandra Bose in 1938.
In 1941, a day before Sarat was arrested by the Britishers, Chaudhuri had quit the job and joined the All India Radio.
Netaji's grandnephew and family spokesperson Chandra Kumar Bose said "it is clear that he was in secret connivance with the Britishers and leaked information about the whereabouts of Sarat, leading to his arrest."
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The family said that after Independence, CBI had investigated the role of Chaudhuri but kept the report secret.
The statement issued by the family said that in late 1967, Sarat's son Amiya Nath Bose had asked Indira Gandhi to show him the CBI file on Chaudhuri. But the then CBI chief D P Kohli refused.
Chandra Bose said Netaji had never liked Nirad C Chaudhuri and used to tell Sarat Bose to sack him.
"By not doing so was the most grievous mistake Sarat Bose made, which ultimately sent him to prison," he said.