Manipur Chief Minister N Biren Singh on Sunday described sheltering of illegal immigrants as the "biggest threat" to the state and announced that a "house-to-house survey" will be conducted soon to identify such people.

Raising serious concern over the influx of illegal immigrants from Bangladesh and Myanmar, Singh told reporters that steps will be initiated against those locals who are allowing such foreigners to live in their houses on rent.

Altogether 613 people were arrested in the past four-five days for violating Inner Line Permit (ILP) norms, the chief minister said.

The ILP is an official document issued by the government to grant inward travel of a person into a protected area for a limited period. The ILP regime came into force in the northeastern state in 2021.

"The recent operations related to Inner Line Permit defaulters were necessitated after many of those entering the state with ILP could not be traced later from the phone numbers they had provided while entering the state," Singh said.

Identifying illegal immigrants has become a huge problem, he said.

"A house-to-house survey will be conducted to find out illegal immigrants. Appropriate actions will be taken against any landlord who shelters illegal immigrants at their place," the chief minister said.

Unless such steps are taken, it will be difficult to save the indigenous population of the state, Singh said.

He urged the local people not to give shelter to illegal immigrants in order to protect the language, culture and identity of the small indigenous population.

"The indigenous population of the state in the whole country is microscopic," he said.

The chief minister said that one of the arrested Bangladeshi men had entered Manipur in 1990 without any valid document.

He later married a local Manipuri woman, procured the Aadhaar card and even bought a piece of land in the state, Singh said.