Chennai,  The Tamil Nadu Police's Special Branch has begun an extensive crackdown on illegal Bangladeshi nationals holed up in various parts of the state, following a tip-off from central intelligence agencies.

Sources in a central agency told IANS said that there were a large number of Bangladeshi nationals in various areas of Tamil Nadu in the guise of West Bengal natives.

The state police have already raided several places and found that the Bangladeshi nationals have Aadhaar cards and have opened bank accounts.

The investigating agencies are tracking the source from where these people have procured the Aadhaar cards.

However, most of these Bangladeshi nationals have used the Aadhaar to create other documents and the police is not able to make out whether these people are from West Bengal or Bangladesh.

Police sources said that most of these Bangladeshis were in industrial areas of Coimbatore, Erode, Tiruppur, and Cuddalore districts, where they were working in various industries.

Some of these Bangladeshi nationals were arrested in cases related to drug-peddling and some in immoral trafficking cases, police said.

The central intelligence agencies also tracking the whereabouts of these Bangladeshi nationals and whether they were involved in any clandestine anti-national activities. While there have already been inputs of certain Maoist organisations having an understanding with some terror organisations, the agencies are probing whether the Bangladeshis in Tamil Nadu are on any particular mission or whether they are here for a living.

While the reports regarding the association of these groups with other anti-national elements is not clear, the intelligence agencies and the state police are not taking any chances given the fact that there are several radical jihadi elements in Bangladesh who get active support from Pakistan-based terror elements.

Pakistan's Inter Services Intelligence (ISI) has also created several sleeper cells in Bangladesh and the Indian agencies are, according to sources, working on the background of these Bangladeshi nationals present in Tamil Nadu.

"We don't know the exact volume of Bangladeshi nationals here. We will, however, flush them out in a few day's time. It's an operation which we are doing quite meticulously and will see results soon," asenior Tamil Nadu Police officer told IANS.