Moulana Obaidur Rahman Fazle was arrested late Monday evening at his father-in-law's house in Jamalpur district, 128 kilometres north of the capital, Dhaka, local Police Chief Noor Akhand said.

A court in Jamalpur on Monday allowed police to keep Fazle, 35, in custody for questioning about the August 17 explosions using over 430 small homemade bombs, Akhand said. Fazle is the younger brother of Abdur Rahman, a fugitive leader of the banned Islamic group Jumatul Mujahedin suspected of carrying out the bombings.

He is also suspected of being a member the group. No one claimed responsibility for the violence, but Jumatul Mujahedin leaflets were found at all the blast sites.

Image: Bangladesh serial blasts

Last weekend, police offered a reward for information leading to the capture of Rahman and Siddiqul Islam, who is suspected of being a leader of Jumatul Mujahedin.

The group wants to establish strict Islamic rule in Muslim-majority Bangladesh, which is governed by secular laws. Authorities have so far detained and questioned more than 300 people, including many suspected Jumatul Mujahedin members, about the attacks, but no one has been charged.

In another development, police raided two shops in downtown Dhaka late on Monday evening and seized "tools and materials" officials suspect were being used for making bombs.