New Delhi, May 16 -- The deadly Easter terror attack in Sri Lanka that claimed 253 lives has put Tamil-speaking Islamist groups on either side of the Palk Strait under the scanner. The National Thowheed Jama'ath (NTJ) is one of the prime suspects that the Sri Lankan government banned in the immediate aftermath of the eight serial blasts, for which the Islamic State (IS) has claimed responsibility.

President Maithripala Sirisena used his emergency powers to ban the NTJ and another group known as the Jamathei Millathu Ibraheem (JMI). Security and counter terrorism experts in Sri Lanka believe the hitherto little-known NTJ to be an organisation that split from the Sri Lanka Thowheed Jamaath (SLTJ) in 2014.

SLTJ, a prominent Muslim outfit tha...