The first year student, Santosh Sahani, of SFI was arrested on April 10 after a clash between Trinamool Congress and Leftsupporters in Siliguri.
The chain was later removed following an uproar with activists alleging violation of human rights, sources said.
Claiming that he was unaware of the student being chained to the hospital bed, North Bengal Development Minister Goutam Deb said, "I called up the superintendent of hospital and jail authorities to remove the chain when human rights activists brought the matter to my notice."
Earlier, Commissioner of Police Anant Kumar told PTI, "He had been in judicial custody and it is for the jail authorities to answer. The police have nothing to do to it."
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CPI(M) leader Asok Bhattacharya went to visit Sahani during the day and found him chained to the bed.
Live footage of the SFI student leader being chained to the bed was shown on television.
"The West Bengal government is claiming that it is a government with a human face. But the condition of human rights in West Bengal is worse than the days of Emergency," Left Front Chairman Biman Bose said.
Human rights activist Sujato Bhadro said it was a gross violation of human rights.
"You can never do such thing with an accused. He is yet to be proved guilty. Even if he is proven guilty you can't chain him when he is under treatment. This is a gross violation of human rights," he said.