Police say security forces have arrested seven suspected members of a banned Islamist group blamed for attacks on foreigners and minority groups in Bangladesh.

Police officer Monirul Islam says those detained in a raid in Mirpur area in the Bangladeshi capital early Thursday included at least three "important figures" of Jumatul Mujahedeen Bangladesh, or JMB.

Islam says the search led to a huge cache of bombs and grenades and other explosives. He says the suspects exploded bombs as the raid started, but no one was injured.

Officials have cordoned off the building and evacuated other residents.

The group was founded in 1998 by Shaikh Abdur Rahman, a religious teacher educated in Saudi Arabia.