Students protest erupted in campuses of at least four Indian universities against the Delhi Police crackdown at Jamia Millia Islamia after last evening's pitched street battles over the new citizenship law that gives Indian nationality to non-Muslim settlers from Bangladesh, Afghanistan and Pakistan.

Students at the Aligarh Muslim University (AMU) had clashed with the police after their solidarity march was stopped and by night both the leading institutions were closed till the first week of January by advancing their winter vacation, reports our New Delhi correspondent.

In solidarity with the students of Jamia Millia and AMU, students of Hyderabad's Maulana Azad Urdu University, Jadavpur University in Kolkata and the Banaras Hindu University in Varanasi took out protest marches after midnight last night.

Braving intense cold in Delhi, hundreds of Jamia Millia students had gathered outside for a night-long demonstration in front of the Delhi Police Headquarters in central Delhi in response to a call from the students of Jawaharlal Nehru University but the protesters dispersed after the Jamia students allegedly involved in violence were freed in the early hours of today.

The trouble in Jamia began on Sunday evening when a protest march by the students snowballed into a pitched battle with the police, vandalism and torching of vehicles.

The police, which used batons and teargas to contain the violence, later barged into the university and detained around 100 students. All the detained students were released around 3:30am local time.

How far behind can IIT Madras be :)

Students stage a protest inside IIT campus against CAA and police brutality on students from Jamia and AMU.#ResistCAApic.twitter.com/L4igs0roFI https://t.co/N7WTCMPhB0

— Srivatsa (@srivatsayb) December 16, 2019

Protests also hit the Aligarh Muslim University with the students, protesting against the amended citizenship law and showing solidarity with their Jamia counterparts, clashed with the police near the campus' main gate.

Officials said at least 60 students were injured in the clashes. The AMU campus has been sealed and heavy patrolling is underway, university officials said today.

Hundreds of students gathered at the trauma centre of the Nehru Medical College Hospital, where the injured are being treated.

CMO Dr Nisar Ahmed said on last count, around 60 students, most of them with trauma injuries and eye injuries caused by tear gas, are being treated.

Aligarh Muslim University Registrar Abdul Hamid said the police entered the campus late Sunday night and clashes were reported from inside. Students have been asked to vacate their hostels, he said.

Scores of Banaras Hindu University students in Varanasi also hit the streets in a protest at the Lanka Gate on Sunday night in support of the AMU students. BHU students from the Left-backed All India Students Association wing, along with other student unions, raised slogans in support of the AMU students.

Ten policemen were also injured in the skirmishes in Aligarh and the police demanded that the students vacate the hostels. Internet has been blocked in Aligarh city and the university closed till January 5 by preponing its winter holidays by a week.

In Delhi, the protest march had started from the Jamia Millia Islamia on Sunday evening and was expected to end at Jantar Mantar, the designated area for protests in the national capital. But violence started soon after. In full view of television cameras, the students clashed with the police and set fire to buses and two-wheelers.

A #JamiaMiliaIslamia Law student expressing her pain about #DelhiPolice behavior yesterday#JamiaProtest #StandWithJamia pic.twitter.com/opu7rQJ1kQ

— Pramod Chaturvedi (@PramodChturvedi) December 16, 2019

In addition to students, several policemen including senior officers were injured. One head constable is in the Intensive Care Unit with severe head injuries.

"The police entered the campus by force and no permission was given. Our staff and students were beaten up and forced to leave the campus," said Waseem Ahmed Khan, chief proctor of the Jamia Millia university.

Senior police officer Chinmaya Biswal told NDTV that the police entered the university only after the violent mob went inside and started hurling stones. "We were checking from where these violent activities were taking place," he said.

Jamia students distanced themselves from the violence. In a statement, the students said "we have time and again maintained our protests are peaceful and non-violent. The violence by certain elements was an attempt to vilify and discredit genuine protests."

Protesting the police action against their fellows, a group of Jamia Millia University students in the morning today stood shirtless outside the university gates.

Defying bone-chilling cold, the group of around 10 students, accompanied by their fellow-students, marched a small distance demanding a Central Bureau of Investigation probe into the "police brutality".

"Our colleagues have been beaten up badly. The policemen entered bathrooms, libraries and beat up girls. Our protest is against the goons called Delhi Police," said a research scholar of the University who did not want to be identified.

As a few women escorted an injured student to narrate their ordeal to the media, some people were seen asking them not to give any statements, reports our New Delhi correspondent.

"We were inside the university when the police had barged in (last night). Around 20 policemen came from gate no. 7 and 50 others came from the rear gate. We told them we were not involved in the violence. They didn't listen. They didn't even spare women," Khanzala, who suffered injuries to the legs and abdomen, said.

Meanwhile, curfew was today relaxed in Guwahati for 15 hours from 6:00am local time with Assam's biggest city limping back to normalcy following week-long protests over the amended Citizenship Act, Assam Police Chief Public Relations Officer Rajiv Saikia said.

Night curfew in Guwahati, however, will remain in force, he said.

In Dibrugarh district, curfew has been eased from 6:00am to 8:00pm.

The students protest in Delhi, Hyderabad, Varanasi and Kolkata came on a day when arson and violence scarred parts of West Bengal during protests against the amended citizenship law aimed at granting Indian citizenship to religious minorities from Pakistan, Afghanistan and Bangladesh living in India was passed by parliament and assented by President Ram Nath Kovind.