Canadian-Bangladeshi Tamim Ahmed Chowdhury and his two associates were killed during an encounter at the militants' hideout.
Counter-Terrorism and Transnational Crime chief Monirul Islam said they got information that Jamaat-ul-Mujahideen Bangladesh chief Musa along with some other JMB terrorists are in Sylhet.
Director of Intelligence Bureau Syed Asif Ibrahim on Sunday said effective intelligence sharing with neighbouring countries like Nepal, Myanmar, and Malayasia, Saudi Arabia would go a long way in helping the country tackle the threat from global terror groups like the Al Qaeda and ISIS.
Procuring ration card, passport, voter ID cards and documents to establish their Indian citizenship are easy and sleeper cells help illegal immigrants in getting them.
However, the US praises India for its significant counter-terrorism actions.
Of the four terrorists, two including a woman were killed on Monday. The bodies of the female terrorist and one man were handed over to police but two others were inside as they were wired or surrounded by explosives.