The NIA on Thursday arrested a Jamaat-ul-Mujahideen Bangladesh (JMB) member and a key co-conspirator in the sensational October 2 Burdwan blast in West Bengal, an agency officer said.
Nurul Hoque alias Naeem (26), who was untraced and on the run since the blast, was arrested by the National Investigation Agency (NIA) near the Howrah railway station.
"Several witnesses and interrogation of other accused revealed Naeem to be a very active JMB member who was operational in Birbhum district in close association with (arrested) Dalim Sheikh and Talha Sheikh (absconding Bangladeshi national)," said an NIA officer.
According to the investigators, Naeem, a resident of Domkal in Murshidabad district, was actively involved in local fund collection drive along with Dalim Sheikh.
"Having undergone training at Mukimnagar madarsa in Murshidabad and Shimulia madarsa in Burdwan district, Naeem was elevated to the position of a trainer," the officer said.
"He actively provided training in arms firing, explosives handling and self-defence techniques in the terrorist training camps of JMB at Shantipally in Birbhum as well as Simulia and Mukimnagar Madrasas," he added.
According to the NIA, as a "motivator" in radicalisation camps, Naeem used to show various video clips of Jehadi orientation to the new recruits, "urging them to join the Jihadi movement with the JMB and take revenge for the atrocities on Muslims worldwide".
Naeem was also a close associate of blast mastermind Sheikh Rehmatullah alias Sajid.
He will be presented before an NIA Special Court on Friday.
The accidental blast took place inside a house in Khagragarh in Burdwan district, killing two JMB militants and injuring another.
The NIA in its charge sheet has indicted 21 people for the JMB's conspiracy to overthrow the existing democratic government in Bangladesh.
Taking up the probe on October 10, the NIA has arraigned 32 people as accused in the case, several of whom are untraced and on the run.
The accused have been charged with a number of offences, including being member of a terrorist gang, commission and conspiracy for terrorist acts, recruitment and funding of terrorist gang, organising terrorist training camps, possession of arms, ammunition and explosive substances, among others.