Ahead of Republic Day, many alerts have been sent to Indian state police chiefs across the country about possible threats.
But the Home Ministry has singled out Rohingya Muslims for special attention, particularly after an assessment that suggests 60 per cent of the 40,000 Rohingya Muslims believed to be in the country were untraceable.
"We had asked states to collate data on Rohingya and the reports that we have got shows the presence of only 15,000.
So the concern is, where did the remaining 24,000 go? That's why we have asked all states to verify their figures again," a senior official at the ministry told media.
The ministry is also concerned that long term visas given to Rohingya till 2016 have either expired or are fast approaching the deadline.
Security agencies are worried that people whose visas are not being renewed may go underground and become potential threats, reports NDTV.
Rohingya - minority Muslims living in the Rakhine state of Myanmar - fled to India, mostly after violence against them peaked last year.
The ministry has sounded an alert to all states, saying that that the whereabouts of those given long term visas should be mapped. An alert sent to states says, "Illegal migrants are prone to recruitment by terrorist organisations and the sense of persecution among Rohingya at the hands of Buddhists can be exploited".
As per the ministry's data, nearly 1100 Rohingya have got long term visas. But no such visa has been renewed after a change in government policy in 2016.
"Most of those who got the visas are staying in Delhi so we have been asked to verify their whereabouts," a senior police official said.
NDTV visited one such colony at Kanchan Kunj near Madanpur Khadar that has seen intense checks. It houses nearly 250 Rohingya, most of whom were given long term visas.
"Earlier, everything was okay but everything has changed in the past year or so.
Checks by various agencies have become more frequent," says Mohd Saleem. In his petition that is being heard by the Supreme Court, he has pleaded that Rohingya be allowed to stay in India till the situation normalises in Myanmar.
"No criminal case on against anyone of us so why are we being targeted. I have petitioned that till the time matter is not resolved government should allow us to stay," he adds.