The National Register of Citizens exercise in Assam has left many lives hanging in balance.

Over the next few months, more than 19 lakh people left out of Assam's final National Register of Citizens (NRC) will try to prove their citizenship before foreigners tribunals set up across the state. While those lucky enough to survive legal scrutiny will be free to reintegrate with society, a less savoury fate awaits the ones who fail.

They will be sent to the country's first full-fledged detention centre, capable of accommodating as many as 3,000 declared foreigners, at Matia in Assam's Goalpara district. And if everything goes according to plan, nine more detention centres of the kind will be set up in the years to come.

Over 1,000 declared foreigners are still housed at prison complexes across the state, desperately seeking salvation in the state's labyrinthine tribunal system.

"We were fed the same food as criminals," said Bacchu Seikh from Karbala, who was recently let out on conditional bail after a Supreme Court order. "We were not kept in the same cells as them, but it was just as bad. There was always the trauma of being in jail, being seen as criminals, branded as foreigners in our own country."

Even with 10 bigger detention centres having a capacity of 3,000 each, there is no real guarantee of change. There are fears of overcrowding, in fact, given the huge number of people excluded from the NRC. "No law of ours prescribes indefinite detention, and the very idea of such a thing is abhorred the world over. Detention centres are basically to keep people who have exhausted all legal remedies, but their number will be huge this time round," said Syed Burhanur Rahman, a lawyer.

Construction work on the detention centre at Assam's Goalpara has been hampered by bad weather.

Ironically, most of the labourers working on the detention centre at Matia don't have their names in the NRC list either. "I fear that I will be unable to prove my citizenship and wind up in detention one day. What will happen then? Everybody in my family, from my children to my aged mother and ailing husband, will suffer," said Sarojini Hajong.

Her husband, 40-year-old Amit Hajong, sells tea and snacks to construction workers just outside the compound. They look content for now, but appearances can be deceiving.

"I, my parents and my two children are in the NRC list but my wife has been excluded. It's causing us a lot of anxiety. We have two children, aged two and five. What will we do if they put her in a detention centre?" asked Amit Hajong.

However, many local residents don't think the detention centres should be viewed as concentration camps. "This is no jail. The facilities here will be much better," said Chandran Kalita, who lives in the neighbourhood.

Meanwhile, officials of the Assam Police Housing Corporation are reeling under deadline pressures brought about by bad weather. "First came the floods, then the rains. We would have finished it long ago, if not for the weather. But come what may, the construction work will be completed by December," said Robin Das, a junior engineer.