As many as 1.9 million people have been left out of the final National Register of Citizens (NRC) for India's border state of Assam and face the prospect of being rendered stateless.
The citizenship list, intended to identify legal residents and weed out illegal immigrants, was published on Saturday.
A total of 3,11,21,004 people were found eligible for inclusion in the final NRC, leaving out 19,06,657 people, including those who did not submit claims.
But the authorities have said that people who did not make the final NRC cannot be declared foreigners until all legal options are exhausted.
Those who are not satisfied with the outcome have been directed to file an appeal before the Foreigners Tribunals.
The time limit to file the appeal has been extended from 60 to 120 days, the authorities said.
On Friday, tens of thousands of paramilitary personnel and police were deployed in Assam ahead of the publication of the citizenship register that could leave millions of people stateless, many of them Muslims, bdnews24.com reports citing Reuters.
For the last four years, residents of Assam have been scrambling to prove their identity in a court-ordered exercise after decades of campaigns by groups complaining about illegal immigrants from neighbouring Bangladesh.
A draft of the citizenship list last year left off four million people, raising the prospects of protests by people facing an uncertain future when the list comes out.