They said the activists were also protesting against the bizarre dress code with several candidates complaining of inconvenience when they came for the test on May 7.
Police said 18 SFI activists were taken into custody for staging the protest without permission.
The protesters also tried to hurl black ink at the CBSE office, police said.
In a shocking incident, a girl in Kerala appearing for NEET was allegedly asked to remove her top innerwear, prompting widespread criticism.
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