Links to a London-based NGO were found to the madrasa at Borhanuddin Upazila, from where the Rapid Action Battalion seized Tuesday a large cache of arms and ammunition, bomb-making materials and equipment.
The elite anticrime force detained four suspected militants including two staffers of Green Crescent Madrasa and Orphanage at Ram Keshobpur in Sachra union, some 20 kilometres from Bhola district headquarters.
Major K M Mamun, leader of the Barisal-8 RAB team that raided the madrasa complex for three hours from 12 noon, said London-based NGO Green Crescent built the madrasa and the orphanage building on 12 acres four years ago.
These started operations three months ago. One 'Faisal' who lives in London but is now in Bangladesh, funds the institutions and oversees the operations.
Major Mamun said they were trying to arrest him.
The recovery includes two pistols, two revolvers, four shotguns, eight magazines, two binoculars, two remote-control devices, 700 pistol and 200 shotgun bullets, 3000 splinters, six life jackets, 20 masks, two walkie-talkies and as many mobile phones.
A number of Jihadi books were also recovered.
The detainees include madrasa trainer 'Russel', 30, caretaker 'Hamid', 30, Abul Kalam, 32, and 'Jasim', 35. All of them have been sent to Barisal RAB camp for interrogation, Major Mamun added.
He said the suspected militants were preparing for a major operation.
There were 11 children aged between 5 and 6 years during the raid at the madrasa, which was heavily secured. A modern bridge that links a big pond to the madrasa remains closed at night. Locals had no idea what was happening inside, he said.
Barisal RAb-8 chief Lt Col Monirul Haq and Bhola police chief GM Azizur Rahman visited the scene.
Rahman told us Tuesday night Faisal was also overseeing operations of the NGO at DaulatKhan Upazila.
He said they hoped to know everything about the operations in a couple of days.
The police chief said the Bhola district has been put on alert after the seizure.
Finance minister AMA Muhith said on Mar 18 the government will examine NGO financing and activities and take strict measures against those found to be channelling funds to militants in Bangladesh.
He said funding of militants came through many sources, through individuals and organisations.
The minister mentioned "the large number of NGOs" approved during the past four-party alliance government by the then social welfare minister Ali Ahsan Muhammad Mojaheed.
The government would audit the accounts and activities of those NGOs meticulously, he added.