A new Indian law that grants citizenship to persecuted Hindus, Sikhs, Buddhists, Jains, Parsis and Christians who fled Muslim-majority Pakistan, Bangladesh and Afghanistan prior to 2015 has led to violent demonstrations.

Indian President Ram Nath Kovind gave his assent to the citizenship bill late on Thursday, signing it into law, an official statement said.

Clearance of the Citizenship (Amendment) Bill triggered widespread protests in eastern state of Assam, as protesters said it would convert thousands of illegal immigrants into legal residents.

Muslims also protested against the law as it does not give them the same rights to citizenship as members of other faiths, a move critics say undermines the secular constitution.

Passage of the bill was a key election promise of Prime Minister Narendra Modi, re-energising his nationalist, Hindu support base.

How did the bill secure parliament's support?

Modi had promised that his party would grant citizenship to the six communities who according to the government have historically faced persecution on grounds of religion in the three Muslim-dominated countries. Lawmakers belonging to his party voted in favour of the bill.

Examine: India's Citizenship Bill has only one aim: protect non-Muslims, harass Muslims

What do critics say?

They accuse Modi's government of drafting rules to favour its hardline Hindu agenda aimed at disturbing permanent settlements belonging to Muslims.

Who does the law leave out?

Opposition parties say the law is discriminatory as it singles out Muslims, who make up nearly 15 per cent of the population. The government says that Pakistan, Afghanistan and Bangladesh are Muslim-majority countries, so Muslims cannot be treated as persecuted minorities.

Who could suffer?

Rights organisations say Modi-supporting lawmakers have cleared the bill to justify the deportation of thousands of Muslims living in the northeastern state of Assam and unable to provide documents to prove Indian citizenship.

What are the discrepancies?

The law does not clarify why minority migrants from Bangladesh, Pakistan and Afghanistan are favoured over those fleeing Sri Lanka and Myanmar from where minority Muslims have sought refuge in India.

What's next?

The law has been challenged in India's Supreme Court by a Muslim political party, lawyers and rights groups on the grounds that it violates the secular constitution.

More than 500 eminent Indian jurists, lawyers, academics and actors have signed a statement condemning the legislation.

Header image: A protester waves an Indian flag during a demonstration against the government's CAB in New Delhi on Friday. — AFP