India's Hindu nationalist government will introduce a controversial bill in the lower House of Parliament (Lok Sabha) on Monday, which will grant citizenship to religious minorities from neighbouring Muslim countries 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first introduced in 2016 by the ruling Bharatiya Janata Party (BJP) government of Prime Minister Narendra Modi but was withdrawn after an alliance partner withdrew support and protests flared in India's remote and ethnically diverse northeast region.

Giving Indian citizenship to "Hindus, Jains, Buddhists and Sikhs escaping persecution" was part of the manifesto of the BJP ahead of a general election in May 2019 that the nationalist party swept.

Amid backlash, the BJP has promised to exclude parts of the northeast from the purview of the bill but that has failed to assuage fears in the region that has historically seen the arrival of undocumented immigrants.

An influential student group, North East Students' Organisation, has announced an 11-hour shutdown on Tuesday against the proposed bill, while Assam-based All Assam Students' Union has threatened to launch "vigorous mass agitation" against the bill.

Last month, India's Minister of Home Affairs Amit Shah announced that his Hindu nationalist government will implement a nationwide count of citizens, amid concerns the exercise could be used to target Muslims.

A similar exercise carried out in Assam state called as National Register of Citizens (NRC) excluded nearly two million from the citizenship list.