Bangladeshi security forces have killed 11 members of a Islamist militant group blamed for an attack on a cafe in Dhaka in July in which 22 people were killed, mostly foreigners.

The 11 militants, believed to be members of Jamaat-ul-Mujahideen Bangladesh (JMB), were killed in three raids on militant hideouts on the outskirts of the capital on Saturday, Home Minister Asaduzzaman Khan said.

Seven militants were killed in a raid on one hideout after police were tipped off that the JMB's Dhaka unit chief and his associates were there.

"We requested them to surrender but they opened fire at our officers, which prompted them to retaliate," Khan said.

The July 1 attack in Dhaka's diplomatic quarter was claimed by Islamic State militants and was one of the most brazen in Bangladesh, which has been hit by a spate of killings of liberals and members of religious minorities in the past year.

The government has blamed domestic militants but security officials say the scale and sophistication of the July attack suggested links to a trans-national Islamist network.

Police have killed more than three dozen suspected militants in shootouts since the Dhaka cafe attack, including its presumed mastermind, Bangladesh-born Canadian citizen Tamim Ahmed Chowdhury.