Police said they obtained orders of Metropolitan Magistrate's court for interrogating the five for three days in their custody while initial investigations suggested the Islamists were all members of the outlawed Jamaatul Mujahideen Bangladesh (JMB).
"All the five JMB members visited Pakistan several times. (One of them) Mohammad Idris alone visited Pakistan 48 times and has contacts with a foreign intelligence agency," a police spokesman told PTI adding that plainclothesmen tracked them down late yesterday in raids in different parts of Dhaka.
"Idris went to Pakistan via India in 1985 and married a Pakistani woman in 1990 and he told us that he also took part in 2002 general elections there but returned to Bangladesh in 2007 and joined the militant outfit JMB," the spokesman said adding that Idris is a Pakistani passport holder.
Bangladesh in the past has arrested several Pakistanis suspecting militant links.
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JMB had carried out near simultaneous 500 blasts in 62 districts of Bangladesh in 2005 that killed two persons.
But the outfit reappeared in the limelight after two of its operatives were killed in October, 2014 in an accidental explosion at a hideout in West Bengal's Burdwan district near the border with Bangladesh.
The blast triggered security alert in both countries with high level exchange of visits by senor security officials and arrest of several JMB activists in India and Bangladesh.