The militant Islamic State (IS) group claimed responsibility late Friday for a suspected suicide bomb attack outside the Bangladeshi capital's main international airport, according to the SITE Intelligence Group, which monitors militant communications.

A bomber was killed in the blast, police said, the third in a series of suspected attacks and the second claimed by the IS group since last week.

The bomb, carried by a man on foot, exploded near a police checkpoint monitoring vehicles heading to Hazrat Shahjahal International Airport in Dhaka.

“The bomb carrier himself was killed,” a Dhaka police spokesman, Yusuf Ali, told AFP.

In an Arabic report, the IS group claimed responsibility for the attack, according to US-based monitoring agency SITE Intelligence Group.

“A martyrdom-seeking attack targeted a Bangladeshi police checkpoint near the international airport in the city of Dhaka,” the IS-linked Amaq news agency said.

Dhaka police chief Asaduzzaman Mia denied it was a suicide attack.

“He was carrying it (the bomb) but we can't confirm yet whether he was trying to attack the check-post,” he said, adding that the bomb carrier was aged around 30.

However, a police officer, who cannot be named, told AFP that they suspected it was a “suicide blast” in which only the “suicide attacker” was killed.

The suspected attack was the third since last Friday, when a suicide bomber blew himself up at a camp for the country's elite security force near the airport.

The attacker was killed and two members of the Rapid Action Battalion, tasked with combating militancy, were injured.

The IS group claimed the attack but the Bangladeshi government deny the presence of IS in the country and rejected the militants' claim.

IS has also claimed responsibility for a wave of killings since 2015 including for a major attack on a Dhaka cafe last year in which 22 people, including 18 foreign hostages, were killed.

The Bangladeshi government argues a new faction of homegrown extremist group Jamayetul Mujahideen Bangladesh (JMB) was behind that and other attacks.

Last Saturday a man on a motorbike tried to cross a RAB security roadblock in Dhaka carrying a bag with improvised explosive devices.

Bangladesh police shot the suspected militant dead.

The latest incident came as police in the northeastern city of Sylhet cordoned off a five-storey building early Friday morning where suspected militants were holed up.

Police have also been carrying out a series of raids in the southern Chittagong region and say they killed four suspected militants when they stormed an extremist hideout last Thursday.