The dispute arose after NSU cadres and UML-affiliated students did not want ANNISU-R member to take part in a programme organised on the occasion of Teej Festivel at the campus premises.
Later they clashed, prompting police to enter the campus premises and use force.
NSU had padlocked the campus since Tuesday, saying that ANNISU-R monopolised in every campus activities.
NSU cadres torch four govt vehicles, take scores in control