Rai said this in a written reply in Rajya Sabha to a query about detention camps in Nagaland on Wednesday.
Union home minister Amit Shah recently announced in the Parliament that a nationwide National Register of Citizens (NRC) will be carried.
The NRC in Assam was carried out under the supervision of the Supreme Court and the final list was declared on August 31 this year.
Over 1.9 million people were left out of the NRC.
The BJP-led Assam government has expressed its dissatisfaction on the final NRC and sought re-verification of a certain population in the districts bordering Bangladesh.
The Supreme Court, however, has rejected the appeal for verification.