KOLKATA - Fresh protests against India's new citizenship law erupted Tuesday as alleged police brutality fueled fury against the legislation which critics say is anti-Muslim.

The law grants citizenship to non-Muslims from three neighboring countries in what opponents say is part of Prime Minister Narendra Modi's Hindu nationalist masterplan.

Uproar over the move has sparked days of protests, clashes and riots across India that have left six people dead and dozens injured in a major challenge to Modi since he swept to power in 2014.

Protesters gathered Tuesday in the eastern city of Kolkata in West Bengal for a fresh rally led by West Bengal Chief Minister Mamata Banerjee, a fierce critic of Modi.

Thousands took to the streets Monday in a march through Kolkata led by Banerjee.

New protests also broke out in the southernmost state of Kerala, while several rallies were planned in the capital New Delhi late Tuesday.

Authorities have imposed internet blackouts and used force to shut down rallies and sit-ins across several states to quell the unrest.

In the northeastern state of Assam, the epicenter of the protests where four people died after being shot by police, a curfew imposed in some regions was lifted early Tuesday.

The new round of rallies came as petitions calling for a probe into allegations of police brutality at two universities in northern India were heard by the Supreme Court Tuesday.

Rioters had torched vehicles while police with batons fired tear gas and charged protesting students before storming Delhi's Jamia Millia Islamia university late Sunday.

The university's vice-chancellor said Monday 200 people were injured but police put the number at 39 students hurt with 30 officers also injured, one of them critically.

Ten people had been arrested for rioting and mob violence but none of them was a student, police told the Hindustan Times on Tuesday.

Human Rights Watch called for police to show restraint, amid claims authorities were using unnecessary or excessive force to quell the unrest in several cities.

Amnesty International also called for police to be investigated over allegations student protesters from Aligarh Muslim University in Uttar Pradesh state were beaten up by officers.

"Students have the right to protest. Violence against peacefully protesting students cannot under any circumstance be justified," Amnesty India's executive director Avinash Kumar said in a statement.

Modi has said Muslims from Pakistan, Bangladesh and Afghanistan are not covered by the citizenship law because they have no need of India's protection. -AFP