Police have reasserted that they are yet to find any possible extremist link to the explosion inside the Pallabi police station in the capital on Wednesday morning.
Meanwhile, the family of one of three arrestees in the blast case has alleged that he was picked up by a "group" two days before his "arrest" early Wednesday in Kalshi area of Mirpur.
Police, however, claimed that they were unaware about the allegation.
Two cases have been filed in connection with the blast that left five people, including four policemen, injured. The three arrestees were each placed on 14-day police remand.
The explosion took place after the three suspects with arms and a weighing machine-like device were detained there amid police's high alert to prevent a possible terror attack.
The Bomb Disposal Unit of the Counter Terrorism and Transnational Crime Unit, under the Dhaka Metropolitan Police (DMP), later claimed that they had defused two more explosives concealed in the weighing machine-like device after securing the area.
Monir Hossain, the joint commissioner (Operation) of DMP heading the three-member probe body, said that they have just started the investigation and have yet to find any militant links to the incident.
DMP Additional Commissioner Abdul Baten also echoed the statement in a briefing on Thursday.
However, hours after the explosion, US-based militant activities monitoring group Site Intelligence said that international extremist group Islamic State had claimed responsibility for the attack.
Baten said that IS can make a claim but all of their claims are not correct. Police's job is to investigate crime. The investigation has nothing to do with who claimed what.
Rejecting the claim, the DMP officer said, "In primary interrogation and investigation, we have found that the three arrestees are involved in criminal activities in Pallabi area and this was an issue of local domination."
Replying to queries at the briefing, Baten said that they were looking into why and how the detainees were planning to commit crimes and who their targets were.
Earlier on Wednesday morning, a bomb – recovered during a raid – went off accidentally when policemen tried to defuse it at the Pallabi police station.
Police said they had arrested Rafiqul Islam, Shahidul Islam and Mosharraf Hossain in the Kalshi graveyard area four hours before the explosion.
Sahidul's elder brother Rafiqul Islam, however, alleged that his brother had been picked up two days before the incident by a group identifying themselves as members of the Detective Branch (DB).
Sahidul was picked up from Bawniyabazer in Kalshi area at around 3:30pm on Monday, Rafiqul told The Business Standard.
He said they had also informed the office of Rapid Action Battalion (RAB) 4 about the "abduction" and filed a general dairy with Pallabi police station regarding the incident.
Asked about the allegation, DMP officer Baten said they were yet to receive any such information. If there is any such statement, police will investigate the issue.
"Police caught the three red-handed and recovered arms and explosives. If there is any issue outside this, police will be able to say only after an investigation," he said
Replying to a question, Baten also said everything cannot be answered instantly and all things cannot be said for the sake of investigation.
Meanwhile, the arrestees were sent to court on Thursday where Metropolitan Magistrate Moinul Islam put them on a 14-day remand each. Pallabi police station officials said the three were taken to the Minto Road office of DB for interrogation.