The Rapid Action Battalion (Rab) yesterday said they suspected that militant Abudullah, who was killed along with six others during an operation at a flat in the capital's Darus Salam, was planning a massive attack on a highrise.

The remarks came after the force recovered a model of a highrise with different kinds of marking from Abdullah's rented flat on the fifth floor of the six-storey building "Kamol Probha".

After clearing the flat of the militant suspect on Wednesday, Rab found remains of seven people, a day after the suspect allegedly detonated bombs there causing a blaze.

In an unnatural death case filed by a Rab deputy assistant director with Darus Salam Police Station yesterday Rab identified five of the dead as Mir Akrabul Karim alias Upal alias Abdullah, 43, his wives Nasrin, 35, and Fatema, 25, sons Osama bin Akrabul, 10, and two-and-a-half-year-old Omar bin Akrabul.

Meanwhile, one Abdul Malek from Elisha of Bhola yesterday claimed that one of the dead was his son, Kamal, 22.

Following autopsy, Dr Sohel Mahmud, head of the forensic medicine department at Dhaka Medical College, said the bodies were burnt but some splinters were found in them.

“The building design was not supposed to be in his flat as it would not match with Abdullah's profession,” said commander Mufti Mahmdu Khan, director of the legal and media wing of Rab.

“He might have planned a massive attack in any highrise building, and for this he piled up huge explosives, some of which were already detonated by himself, while some others were recovered by our bomb disposal unit,” he said while briefing journalists on the spot in the evening.

The Rab official, however, did not disclose any location or details of the highrise.

Rab personnel also recovered 10 big-size bombs and found 30 unique types of "bottle bombs" made with different chemicals, 10kg of gun powder, 50 locally made sharp weapons, and bomb-making materials including sulphur from the flat yesterday. 

They suspended the search operation till morning today. When the operation resumes today, they will search another flat of the house where 23 big refrigerators and many sealed cartoons are still to be checked.

He said they were now looking for one "Don Bhai" and six others employed by Abdullah. Abdullah disclosed the name of Don to Rab officials during their hours of negotiations with Abdullah about his surrender, Rab officials said.

Meanwhile, two people including owner of the house in Darus Salam area, where remains of seven people were found yesterday, were arrested for their alleged involvement in militancy.

Habibullah Bahar Azad, owner of the building, and night guard Sirajul Islam were arrested as their connection with the militants were found, said Khandker Lutful Kabir, commanding officer of Rab-4.

They were shown arrested in a case filed earlier in April in connection with the arrest of militant suspect Tamim Dari.

The duo will be interrogated in remand to get more information, the Rab official said.

Dari, who is said to be a jihadist who converted from Hinduism,  and two others, all members Sarowar-Tamim group of JMB, were arrested in Savar on April 27. 

In another development, Biman Bangladesh Airlines authorities yesterday asked first officer Sabbir Ahmed, son of the house owner Habibullah Bahar, not to pilot any flight.

A top Biman official said as Sabbir, a copilot, was disturbed by the arrest of his father and discovery of a militant den in their house, the authorities asked him to remain off duty for a few days considering flight safety.

Rab yesterday claimed that Abdullah's family refused to accept his body.