India on Monday effectively stripped more than four million people in Assam of citizenship, sparking fears of mass deportations of Muslims from the northeastern state.
A new draft register of citizens includes only those able to prove they were in Assam before 1971, when millions fled Bangladesh's war of independence into the state, and their descendants.
Critics say it is the latest move by the right-wing government of Prime Minister Narendra Modi to bolster India's Hindu majority at the expense of minorities. India will hold a national election next year.
Officials said security had been tightened across the state as thousands of Bengali-speaking Muslims worry about being sent to detention centers or deported. News of the draft register sparked opposition protests in the national parliament, forcing the adjournment of upper-chamber hearings for the day.
Soldiers stood guard at government offices, where thousands of people queued to check their names on the so-called National Register of Citizens (NRC), Reuters witnesses said.
The list was uploaded on a government website, but many in remote regions of Assam, who lack internet connectivity, traveled to government booths set up for the exercise to determine their status.
Of more than 32 million people who submitted documents to prove their citizenship, the names of 4,007,707 were missing, said Shailesh, the registrar general of India, who uses one name.
"No genuine Indian citizens need to worry as there will be ample opportunities given to them to enlist their names in the final list," he told a news conference in Assam's biggest city Guwahati.
He said appeals could be made under "well-laid-down procedures" starting August 30. The definitive list is to be finalized in December.
"We are going to provide assistance to anyone whose names are not included in the document and whoever wishes to file a claim and objection in this regard," Shailesh added.
Modi's Bharatiya Janata Party (BJP) won control of Assam in 2016 after promising to expel illegal immigrants from mainly Muslim Bangladesh and protect the rights of indigenous groups.
Assam, where one third of the population is Muslim, is the only Indian state to compile a register of citizens.
- Migrant fears -
Hundreds of thousands fled to India from Bangladesh during its 1971 war of independence from Pakistan. Most settled in Assam, which shares a long border with Bangladesh.
Migrants have since been accused of illegally entering the state and taking land and jobs, causing tensions with locals.
Rights groups have criticized the government move, saying deletion from citizenship lists was similar to Myanmar's removal of rights and protections for its Rohingya community in 1982.
Avaaz, a US-based activist group slammed the Indian action.
"It's just Muslims who will likely have to go through a complicated, unfair appeal with no right to counsel, ending in no hope of staying if they lose," Ricken Patel, the executive director of Avaaz, said in a statement.
Assam, a state of 33 million people known for its lush tea estates, has for decades been racked by violence between indigenous tribes and settlers.
About 2,000 suspected migrants were butchered in a single day in Nellie in 1983. Nearly all were Muslim, and many were children.
The country's Supreme Court, which has been supervising the registration, had initially set June 30 as the deadline to publish the draft list.
But this was postponed to July 30 because the massive exercise could not be completed in time.
A first draft published last December included only 19 million people as legal citizens.
In New Delhi, Home Minister Rajnath Singh also sought to allay fears about Assam.
"No coercive action will be taken against anyone. Hence there is no need to panic," Singh said in parliament.
Satyendra Garg, a home ministry official who was at the Guwahati press conference, said there "was no question of sending anyone to detention camps based on the draft list".
The Assam controversy comes as the government looks at amending the citizenship law to allow certain "persecuted minorities", including Hindus and Christians from neighboring countries, to obtain legal status after six years of residency in India.
Other groups must wait 11 years to become naturalized citizens.
