DHAKA (AFP) - United States Secretary of State John Kerry said on Monday (Aug 29) that there was evidence to link the extremists behind a recent series of deadly attacks in Bangladesh to the Islamic State in Iraq and Syria (ISIS).

"We talked very openly about this and we made it very clear ... that there is evidence that ISIL in Iraq and Syria has contacts with about eight different entities around the world and one of them is in South Asia," he said after talks with Bangladeshi government officials.

"They are connected to some degree with some of the operatives here and we made that very clear in our conversation. There was no argument about it."

ISIS has claimed responsibility for last month's deadly attack on a cafe in the Bangladeshi capital Dhaka in which 22 people were killed and pictures of the attackers holding IS flags were posted online.

Despite a string of attacks being claimed by ISIS or a branch of Al-Qaeda, Prime Minister Sheikh Hasina's government has consistently denied any international jihadist network has gained a foothold in Bangladesh.

Mr Kerry however rejected the idea that Ms Hasina's administration was in denial about the nature of the extremist threat that it faced.

"I don't believe that the government of Bangladesh has its head in the sand. I do not believe that," he said in a speech in Dhaka where he was paying a one-day visit.

The top US diplomat said that the two governments had agreed on increased cooperation between their respective intelligence agencies.

"The (Foreign) Minister (Mahmood Ali) was very, and the Prime Minister was very clear (at) the desire to cooperate with us very very closely," he said.

"We today agreed on additional steps by which our intelligence and law enforcement will work together in order to try to get ahead of this.

"And we talked about all aspects of it including the importance of inclusivity, working with people, making sure that (you) protect the democratic process even as you come down tough on the perpetrators themselves."