A controversial bill, which will grant citizenship to religious minorities from India's neighbouring countries, was passed in the lower House of Parliament (Lok Sabha) on Monday amid concerns it violates the spirit of the country's secular constitution.
The Citizenship Amendment Bill (CAB) seeks to amend 1955 law to grant citizenship to Hindus, Buddhists, Jains, Christians, Sikhs and Parsis facing persecution in Pakistan, Bangladesh and Afghanistan - but excludes Muslims.
Activists and some opposition parties have said the proposed law is discriminatory, in what critics say is a fresh attempt to sideline the nearly 200-million-strong Muslim minority.
Shashi Tharoor, whose Congress party has decided to oppose the bill, called it a "fundamentally unconstitutional" piece of legislation.
The bill will easily be passed in the lower house where the BJP enjoys a majority but is short of numbers in the upper house (Rajya Sabha). Any bill needs to be ratified by both houses of Parliament to become law.
India's cabinet approved the draft law on Wednesday triggering protests in the country's northeast region, which fears tens of thousands of Hindus from neighbouring Bangladesh would gain citizenship.
The CAB was first introduced in 2016 by the ruling Bharatiya Janata Party (BJP) government of Prime Minister Narendra Modi but was withdrawn after an alliance partner withdrew support and protests flared in India's remote and ethnically diverse northeast region. _Al-Jazeera