Policemen detain an injured student outside the Jamia Millia Islamia university during a protest against the Citizenship Amendment Act in New Delhi, India, Dec 15, 2019. (SAALIQ SHEIKH / AP)

NEW DELHI - Protests over a new Indian citizenship law based on religion spread to student campuses on Monday as critics said the Hindu nationalist government was pushing a partisan agenda in conflict with the country's founding as a secular republic.

Students pelted stones at police who locked up the gates of a college in the northern city of Lucknow to prevent them from taking to the streets. About two dozen students at another college in the city sneaked out to protest.

Anger with Prime Minister Narendra Modi's Hindu nationalist government was further fueled by allegations of police brutality at Jamia Millia Islamia university on Sunday, when officers entered the campus in the capital New Delhi and fired tear gas to break up a protest. At least 100 people were injured in the clashes there.

There were similar scenes at the Aligarh Muslim University (AMU) in the northern state of Uttar Pradesh, where police also clashed with protesters on the campus.

At least 100 were injured in clashes at the Jamia Millia Islamia university in New Delhi on Sunday

ALSO READ: Fallout from India’s citizenship law spirals as Abe trip on hold

Modi said Monday that the ongoing violent protests on the Citizenship Amendment Act (CAA) were "unfortunate and deeply distressing", Xinhua reports.

"I want to unequivocally assure my fellow Indians that CAA does not affect any citizen of India of any religion. No Indian has anything to worry regarding this Act. This Act is only for those who have faced years of persecution outside and have no other place to go except India," tweeted the Indian prime minister.

Officials said authorities have now extended the internet ban to Uttar Pradesh's Aligarh, Meerut and Saharanpur, according to Xinhua. The internet ban has also been imposed in parts of the eastern state of West Bengal after violent protests erupted against the new law. According to officials, the internet has been blocked in six districts and four subdivisions.

The ban is already in place in parts of three northeastern states of Assam, Tripura and Meghalaya since last week. Authorities justify the ban on internet, saying it helps in preventing the circulation of information that has the potential to incite violence.

"We ordered the suspension of the internet as a precautionary measure in some parts until this morning but today again we extended it for another 24 hours in districts -- Lakhimpur, Tinsukia, Dhemaji, Dibrugarh, Charaideo, Sivasagar, Jorhat, Golaghat and Kamrup," an official in Guwahati said. "If the situation will improve completely then we will restore the service."

A person walks past a street strewn with bricks and pebbles outside the Jamia Millia Islamia university after a protest against the Citizenship Amendment Act in New Delhi, India, Dec 15, 2019. (SAALIQ SHEIKH / AP)

Under the law passed by parliament last week, religious minorities such as Hindus and Christians in neighboring Bangladesh, Pakistan and Afghanistan who have settled in India prior to 2015 will have a path to Indian citizenship on grounds they faced persecution in those countries.

Critics say the law, which does not make the same provision for Muslims, weakens India's secular foundations.

I want to unequivocally assure my fellow Indians that CAA does not affect any citizen of India of any religion. No Indian has anything to worry regarding this Act. This Act is only for those who have faced years of persecution outside and have no other place to go except India.

Indian Prime Minister Narendra Modi's tweet

The head of Jamia Millia demanded an investigation into how police were allowed to enter the campus. "It is not expected of the police to enter the university and beat up students," Najma Akhtar said at a news conference.

Students said police fired tear gas and windows were broken in the library. They ducked under desks and switched off the lights as advised by teachers.

Hundreds of people gathered outside the New Delhi police headquarters to protest against alleged police brutality and the detention of students. Police said they acted with restraint.

ALSO READ: India: Protesters set fire to train stations over citizenship law

Rahul Gandhi, the leader of the main opposition Congress party, said the Modi government was dividing up Indian society through the citizenship law and a plan to launch a national citizenship register.

"The best defence against these dirty weapons is peaceful, non-violent Satyagraha," he said in a tweet referring to the strategy of passive political resistance advocated by independence leader Mahatma Gandhi.

The most violent protests during the past few day took place in the northeastern state of Assam, where mobs torched buildings and train stations, angry the law would help thousands of immigrants from Bangladesh become lawful citizens. At least two people were killed in the violent clashes with police.

Passenger buses go up in flames during a protest against Citizenship Amendment Act in New Delhi, India, Dec 15, 2019. (PHOTO / AP)

Protests were held in Mumbai's Indian Institute of Technology and Tata Institute of Social Sciences overnight and on Monday and more were planned at Bombay University and in the southern city of Bengaluru later in the day.

Some Bollywood celebrities like actress Konkona Sen Sharma, and directors Mahesh Bhatt and Anubhav Sinha, also criticized the police action on Twitter, and called on others to speak up.

"We are with the students! Shame on you @DelhiPolice," Sen Sharma tweeted.

Modi's ruling Bharatiya Janata Party denies any religious bias but says it is opposed to the appeasement of one community.

It says the new law is meant to help minority groups facing persecution in the three nearby Muslim countries.

Modi has said the law has been passed by parliament and there is no going back on it  He told a rally on Sunday the decision was "1000 percent correct."

With Xinhua inputs