Three alleged members of a Bangladesh-based terror group were arrested at Charbagh railway station in Lucknow on Wednesday.Identifying the trio – Mohd Imran, Rajidudeen and Mohd Firdaus – as brothers who illegally immigrated to India, state anti-terrorist squad (ATS) inspector general of police Asim Arun said they had been staying in west Uttar Pradesh for the last few years on the basis of fake Aadhaar cards. The accused were taken into custody while boarding the Amritsar-Howrah Express, so they could return to Bangladesh via West Bengal.The three, said to be part of the al Qaeda-inspired Ansarullah Bangla Team (ABT), hail from Jasor district in Bangladesh. They had been staying at Deoband in Saharanpur district for a while now, and one of the brothers – Mohd Imran – even landed a teaching job at a local madrassa.Arun said the names of the three brothers came to light during the interrogation of Abdullah-al-Mammon, a key ABT operative who was arrested from Muzaffarnagar on August 5. The accused had reportedly gone missing soon after Mammon’s arrest.The case is being investigated by an ATS team led by additional superintendent of police Rajesh Sahani, and efforts are on to gain police custody of the accused – so further information can be gleaned.Arun said Mammon’s arrest has exposed a wide network of illegal Bangladeshi immigrants in the state. He has confessed to creating fake identification documents – such as Aadhaar cards – for such people since 2011. The police officer said that Mammon received his own fake identification documents, including an Indian passport, with the help of another key ABT operative called Faizan. “However, Faizan managed to escape because the ATS reached his Saharanpur residence,” Arun said, adding that a hunt is on to locate him.Mammon and Faizan allegedly accommodated illegal immigrants in slums across the region, and even provided them with jobs. They are also accused of preparing a large network of sleeping modules across the country by sending illegal immigrants to various cities.