India moved thousands of troops into the northeastern state of Assam yesterday as violent protests erupted against a new law that would make it easier for non-Muslim minorities from some neighbouring countries to seek Indian citizenship.
Prime Minister Narendra Modi's Bharatiya Janata Party-led government has said the Citizenship Amendment Bill is meant to protect besieged minorities.
Critics say it undermines the country's secular constitution by not offering protection to Muslims while others argue it will open India's northern states to a flood of foreigners.
Resistance to the bill has been the strongest in Assam, where a movement against illegal immigrants from neighbouring Bangladesh has simmered for decades.
As India's upper house of parliament passed the bill in the early hours of Thursday, protests took place across the northeast.
In Assam, protesters defied a curfew, torching cars and tyres and chanting anti-Modi slogans.
While the streets of Assam's capital Guwahati were largely calm as troops moved in from neighbouring states, protesters were back on the streets in other parts like Morigaon, where they burnt tyres.
Mobile Internet was suspended in some parts of Assam with the government saying that social media platforms could potentially be used to "inflame passions and thus exacerbate the law and order situation".
"A landmark day for India and our nation's ethos of compassion and brotherhood!," Mr Modi tweeted after the citizenship law was apssed on Wednesday. "This Bill will alleviate the suffering of many who faced persecution for years."
Opponents of the legislation have threatened to challenge it in the Supreme Court, saying it violates the principles of equality and secularism enshrined in the constitution.
"The bill will take away our rights, language and culture with millions of Bangladeshis getting citizenship," said Gitimoni Dutta, a college student, in Guwahati.
Despite assurances from Home Minister Amit Shah that safeguards will be put in place, people in Assam and surrounding states fear that arriving settlers could increase competition for land and upset the region's demographic balance.
The Citizenship Amendment Bill seeks to grant Indian nationality to Buddhists, Christians, Hindus, Jains, Parsis and Sikhs who fled Afghanistan, Bangladesh and Pakistan before 2015.
The bill passed the upper house of parliament with 125 members supporting it and 105 opposing. It will be sent to the president to be signed into law, with his approval seen as a formality.
The government said Muslims from Afghanistan, Bangladesh and Pakistan are excluded from the legislation because they do not face discrimination in those countries.
In response, Bangladesh's Foreign Minister A.K. Abdul Momen told news agency UNB on Wednesday that his country did not oppress minorities.
"In our country, religious harmony is at a very high level. No one from other religions is oppressed here... We see those (minorities) in equal eyes and as the citizens of Bangladesh."
The United States Commission on International Religious Freedom said on Monday that Washington should consider sanctions against Mr Shah, a close associate of Mr Modi, if India adopts the legislation.
"The passage of the Citizenship Amendment Bill marks the victory of narrow-minded and bigoted forces over India's pluralism," said Mrs Sonia Gandhi, leader of the main opposition Congress party.
Defending the bill in the upper house, Mr Shah said the new law sought to help only minorities persecuted in Muslim-majority countries contiguous with India.
"Nobody is taking citizenship away from India's Muslims. This is a bill to give citizenship, not take citizenship away," Mr Shah said.