Police in Bangla­desh arrested on Sunday four female members of a home-grown militant group blamed for a bloody attack on a cafe in which 22 people were killed, most of them foreigners, an officer said.

Authorities have intensified a hunt for militants after five young men stormed the upmarket restaurant popular with foreigners on July 1. Among those killed were nine Italians, seven Japanese, an American and an Indian. The five militants were gunned down when security forces moved in.

Police believe that Jamaat-ul-Mujahideen Bangladesh (JMB), a banned group that has pledged allegiance to the IS, played a significant role in organising the group of privileged, educated young men who carried out the attack.

The four women members of the group, aged 18 to 30, who were arrested in from the north-western district of Sirajganj, were believed to have been plotting an attack, police said. “Acting on a tip-off, our force raided a rented house where a large amount of grenade-making materials, crude bombs and jihadi books were also found,” district police superintendent Siraj­uddin Ahmed told reporters.

The women would be interrogated to determine if they had any link to the Dhaka cafe attack, he said.