Three Bangladeshi brothers, suspected to have links with militant group Ansarullah Bangla Team, have been arrested by the Anti-Terrorist Squad of India's northern state of Uttar Pradesh, a senior police official said yesterday.

The trio -- identified as Mohammad Imran, Rajiuddin and Mohammad Firdaus -- were arrested in Lucknow, the state's capital city, when they were about to board Howrah-Amritsar Express train on Wednesday afternoon, ATS Inspector General Asim Arun said.

During interrogation, the three youths confessed that they were residents of Bangladesh, and fake Aadhaar multipurpose cards of India were found in their possession.

Aadhaar is allocated to every Indian and remains their national identity document forever.

Asim said that they were later put under arrest.

This was the second time in just over a month that Bangladeshi nationals were held by Uttar Pradesh ATS for suspected links with Ansarullah.

The names of the three brothers cropped up after an ATS team on August 6  arrested a suspected Bangladeshi terrorist, Abdullah al-Mamun, a resident of Mymensingh, from Muzaffarnagar district of the state.

During the questioning of Abdullah, the name of some persons came to the fore and a probe was done in Deoband madrasas to find his links, Asim said.

It was found that three persons -- a madrasa teacher and his two brothers -- were missing after which ATS team swung into action and the three were arrested.

He said the ATS would probe why they fled from Deoband, where the leading seminary Darul Uloom is located, and whether they have links with any other terrorist group.

Abdullah, who was arrested from Kutesara locality in Charthawal area of Muzaffarnagar district, had been staying in the area for a month.

Earlier, he had resided in Deoband area of Saharanpur since 2011 and had also got his Aadhar card and Indian passport prepared on fake identity.

ATS officials said Abdullah is associated with Ansarullah Bangla Team and was involved in preparing fake identity proofs of terrorists especially of Bangladesh and help them get safe hideouts in India.

During interrogation, Abdullah told ATS that he used to prepare fake identity proofs with the help of one Faizan, a resident of Deoband (Saharanpur), IG ATS said.

Based on this input, Faizan's house was searched in Deoband but he was not found there.

Officers recovered “jihadi” literature in Bangla, literature for making bombs, a colour printer and a number of fake IDs from the house.

Asked about it, Saiful Islam, additional deputy commissioner of counterterrorism and transnational crime unit of Dhaka Metropolitan Police, told The Daily Star yesterday that they are inquiring about the three arrestees in India.