According to students and teachers present there, the attacker called Kanhaiya for an interaction when he was attending the "nationalism" lecture at the varsity's administration block.
"Kanhaiya went to a corner to talk to him where the man started abusing him and, following an argument, slapped him. Seeing this, many students and university's security guards rushed to rescue him," a student said.
The varsity's security held the accused man, who identified himself as Vikas Chaudhary, a builder from Ghaziabad, detained him at the administration block and called police.
University authorities, when contacted said, they have got to know about the attack from media reports and whether or not they will approach the police will be decided tomorrow.
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Chaudhary told reporters, "Kanhaiya has abused the nation, he has abused our Army by raising allegations against our soldiers. He shouted anti-national slogans and also sided with anti-national people, that is why I attacked him".
He was granted interim bail for six months by the Delhi High Court last week after spending 18 days in jail.
The students and teachers of the varsity had expressed apprehension about Kanhaiya's security after he was attacked by a group of lawyers in Patiala Court premises on February 17. The Delhi police has asked the varsity authorities to intimate them about Kanhaiya's movements outside the campus.
A man who claimed to be the president of "Purvanchal Sena" had last week announced a reward of Rs 11 lakh for anyone who shoots Kanhaiya. He was later arrested.