Rapid Action Battalion (Rab) will be quizzing him to find out the origins of the explosives recovered at Daulatpur of the city on Friday. Sources said Mohammad Ziaur Rahman Sagor alias Shabbir was arrested at Tootpara in Khulna city on Thursday night.

A senior officer of intelligence agency of Khulna Metropolitan Police (KMP) said a vigorous investigation is going on to find out links between a ward level BNP leader and Shabbir.

Shabbir told police he used to come to Khulna frequently from Jessore to supply money, explosives and instructions from operations commander in the south-western region Hafez Mahmud to other JMB cadres. He said there are seven more 'Ehsars', the first tier of JMB and full-time JMB workers, at large who are trained for suicide bomb attacks.

A student of Dakhil madrasa in Natore, Shabbir failed twice in the Dakhil examination in 2000 and 2002. "I joined JMB last year at the call of Bangla Bhai," said the JMB deputy operations commander in Khulna. He said he along with some other JMB cadres stayed at the house of Abdul Hakim, a teacher of St Josheph's School in Bagmara of Khulna.

Deputy Commissioner Akbar Ali of KMP told The Daily Star yesterday the police and Rab are committed to crushing the JMB network in Khulna.

Meanwhile, security in Khulna city has been tightened ahead of New Year's celebrations following the arrest of JMB cadres and explosives haul.