The Left Front alleged that Banerjee was trying to establish the death as an "accident".
Sudipto Gupta, 22, a post-graduate student of the Rabindra Bharati University and West Bengal state committee member of the SFI, the students' wing of the CPI(M), died Tuesday evening at a state-run hospital amid allegations that a baton charge by police led to his fatal injury.
Police, however, said that the activist died after he crashed into a lamp post while being taken to jail.
The Left Front said Banerjee's comment on Gupta's death before any inquiry was "wrong" and the incident was being shown as an "accident".
Banerjee, who visited the hospital Wednesday afternoon, said the incident was "unfortunate". She added that many activists of her party had been killed when they crashed into lamp posts while travelling by trains.
"The chief minister has made some comments. She is not only a chief minister but also holds the home portfolio. If she comments on the death, then is there any scope of an inquiry," state Left Front chairman and CPI(M) state secretary Biman Bose told a media conference here.
"It is wrong of the chief minister to comment before an inquiry has been conducted. That is not expected from a chief minister. She should learn how a chief minister should behave," Bose said.
Stating that the case "was being shown as an accident", the CPI(M) leader said: "We had earlier demanded a judicial probe into the shocking death of Gupta. But after the chief minister's comments, the inquiry will be of no use."
Holding the police responsible for the SFI activist's death, he demanded swift punishment for the culprits.