At least six persons, including two police officials, were killed and over 40 were injured in two explosions on Saturday near a militant hideout in Sylhet city, some 240 km from capital Dhaka.

Sylhet Metropolitan Police Additional Deputy Commissioner Zedan Al Musa confirmed the death toll to early on Sunday.

The explosions came a day after a suicide bomber blew himself up at a security checkpoint near the country's main airport in Dhaka in an attack claimed by Islamic State.

Of those seriously wounded include Rapid Action Battalion (RAB) Intelligence chief who has been airlifted to Dhaka for better treatment.

One of the injured persons, Gulzar Ahmed, told  that some onlookers stopped a person carrying a black polythene bag.

"The blast occurred just after he said that there was red spinach in the bag. Five to six people were injured in the explosion," he said.

"Another large explosion occurred when police and RAB rushed to the scene. Around 25 people were injured in the second blast," he added.

Witnesses earlier said two people riding a motorcycle 'carried out an explosion' at one end of the street where the militant hideout is located.

The blasts came within an hour of a media briefing on a raid at the militant hideout in which an army spokesperson said the commandos were storming a complex housing two buildings -- one five-storey and the other four-storey.

Mediapersons and onlookers in the area were asked to move at least a kilometre away when troops from the Para-Commando Battalion began the assault on Saturday morning to round off a 30-hour siege to the complex.

Police said the militants rented a flat some months ago. The 30 families residing in as many other units of the buildings were trapped during the raid.