A British national and a student at a Canadian university were arrested on Wednesday night on suspicion of their involvement in the deadly Gulshan cafe attack in Dhaka, police said on Thursday.

Police spokesman A.K.M Shahidur Rahman said Hasnat Karim, who is a Bangladeshi origin British citizen, and Tahmid Khan, a student at the University of Toronto, were detained for interrogation.

"We can confirm that they were arrested under Section 54 of CrPC (criminal procedure)," Rahman told AFP.

Karim and Khan were both present inside the Holey Artisan Bakery cafe when the militants raided the premises on July 1 and killed 22 people.

But none of them was seen in public after the attack when the commandos stormed into the restaurant.

However, their families insisted that there is no evidence to link Karim and Khan to the attackers. The families claimed that they were innocent bystanders and were being unnecessarily held by the security services.