Security forces have killed at least four militants, including a woman, who were holed up in a residential building in Bangladesh's Sylhet city, a military spokesman said on Monday.

Brigadier General Fakhrul Ahsan, a spokesperson of the operation, told journalists at a press briefing that they found four bodies inside the building.

"We've recovered two bodies and contemplating options to recover the two other bodies with suicidal vests," media said.

A huge cache of explosives has been found scattered inside the building , Ahsan said, adding that a portion of the building may collapse if they explode. "So we need to move very carefully," he added.

But he said the multi-storeyed building, 'Atia Mahal', where the terrorists were holed up was now under their control.

"Three of the militants killed were men and one a woman," he added.

The identity of the killed militants was not immediately known.

He said the "Operation Twilight" that began on Friday will continue.

With the recovery of bodies of the four militants from the hideout, the death toll in the operation stood at 10 as six persons, including two policemen, were killed and dozens of others injured in two explosions on Saturday near the hideout.

The Islamic State (IS) reportedly claimed responsibility for the blasts.

On Friday, Sylhet police and personnel from police's counterterrorism unit cordoned off a housing complex at Shibbari neighbourhood, some 240 km from capital Dhaka.

Bangladesh Army Para-Commando Battalion took charge of the operation from the police on Saturday and began the assault on the complex housing a five-storey and a four-storey building.

The same Bangladeshi commandos stormed the Holey Artisan Bakery in Dhaka's diplomatic enclave Gulshan on July 2 last year.

In the wake of the Dhaka cafe attack, Bangladesh has conducted a series of large-scale operations against militants.

Bangladeshi police have hunted down and killed scores of militants linked to the terror attack on the Holey Artisan Bakery, in which 20 hostages, mostly foreigners, were killed

Neo-JMB (an offshoot of the banned militant outfit Jamaatul Mujahideen Bangladesh) was blamed for the attack..