A man places a sign as others light candles during a vigil in Kolkata, India, to show solidarity with the victims of the attack at Holey Artisan restaurant after Islamist militants attacked the upscale cafe in Dhaka, Bangladesh, July 2, 2016. [Photo/Agencies]

Meanwhile, the US State Department said a US citizen was among those killed in the attack.

"We can confirm that a US citizen was also among those senselessly murdered in this attack," the department said in a statement.

Chowdhury told a press briefing that six attackers were killed during an armed raid on Saturday morning that ended the 13-hour siege in Gulshan.

"We've managed to capture one attacker alive," he said.

Some 13 hostages, including one Japanese and two Sri Lankans, were rescued.

Around five hours into the attack, according to a jihadist threat monitoring portal, SITE Intelligence Group, IS claimed responsibility of attacking the upmarket restaurant.

The gunmen stormed the restaurant in Dhaka's diplomatic enclave Gulshan on Friday night.

The authenticity of the IS claim has not been confirmed by the Bangladesh police.