Describing the violence outside Ramjas College here as an example of "state machinery backed violent intolerance", the CPI-M on Thursday demanded action against ABVP activists involved in the assault as also against the police for connivance.

Wednesday's clashes between the RSS-backed Akhil Bharatiya Vidyarthi Parishad (ABVP) and Left-leaning All India Students Union (AISA) left over a dozen people injured.

The violence erupted a day after the ABVP forced the suspension of an event to be addressed by JNU student Umar Khalid, jailed last year for sedition.

Police have registered a case against unknown persons for rioting and assault on public servants.

The Communist Party of India-Marxist condemned the violence by ABVP "goons" and denounced the Delhi Police.

"This is another shameful example of the violent intolerance backed by the state machinery of the RSS-BJP combine and its various wings against all forms of democratic protest, particularly in universities," it said.

"Delhi Police played the shameful role of facilitator for the ABVP goons and stood by while the protesters were being stoned by them.

"Students and teachers including from the Delhi University Teachers Association and the Academic Council who were marching to the local police station to protest were attacked by the police," it said.

"The CPI-M demands that all those who indulged in violence to disrupt the seminar and attack the democratic protest should be arrested. Action must be taken against the Delhi Police personnel who connived with the ABVP."