The initiative started on Friday and follows the murders of members of religious minorities, secular bloggers, gay rights activists and academics in recent months.

The SITE Intelligence Group says the "Islamic State" (IS) group claimed responsibility for killing a Hindu monastery worker on Friday morning.

Some 40 people have been killed by jihadis in the majority Muslim country over the past three years, police believe. In recent weeks, attacks claimed the lives of a Hindu trader, a homeopathic doctor and a Buddhist monk.

Experts have said the terror groups IS and al Qaeda are expanding their operations in the South Asian country. Both have claimed responsibility for some of the attacks although the government has blamed them on local Islamist groups.

Crackdown starts

Officers and paramilitary soldiers fanned out across the country Thursday night to raid suspected militant hideouts, police spokesman Kamrul Islam said.

Islam said the detainees included only 37 alleged radical Islamist militants.

Prime Minister Sheikh Hasina announced the planned anti-militancy campaign after the wife of a police superintendent was shot and stabbed to death on June 5.

Suspected extremists killed the 30-year old Mahmuda Khanam Mitu, wife of Babul Akter, the police superintendent in Bangladesh’s second-biggest city, Chittagong. She was only the second woman killed by extremists in the recent attacks.

The attack followed her husband's promotion in the fight against banned Islamist extremist groups, such as Jamaat ul-Mujahideen Bangladesh.

jbh/rc (AP, dpa)