The Jama'atul Mujahideen Bangladesh (JMB) militants threw home-made bombs, wounding three police, before they were overpowered, according to police. Guns, explosives and other weapons were found at the scene.

The arrests were made some 300 km (186 miles) north of Dhaka in Rangpur district, where Kunio Hoshi, a 65-year-old agriculturalist, was killed while working on a farming project in the impoverished, mostly Muslim country.

Mizanur Rahman, a police superintendent in Rangpur, told reporters that two of the men arrested, Belal Hossain and Ershad Alam, had helped train the militants who had killed Hoshi.

The other men arrested, Ashraful Islam and Al Amin, were JMB activists, he said.

In July, police lodged a charge sheet against eight JMB members, including ringleaders Saddam Hossain and Masud Rana, who were said to be involved in Hoshi's killing.

A JMB splinter group, that has aligned with Islamic State, claimed responsibility for the attack in July on a restaurant in an upscale neighborhood of Dhaka that killed 22 people, mostly foreigners. Two police and five gunmen were also killed during the gunbattle at the restaurant.