"A Dhaka court granted us two days against our plea seeking a seven-day remand for Sheikh Mozaffar Bin Mohsin in connection with the murder of Nurul Islam Farooqui," a police spokesman told PTI.
Metropolitan Magistrate Tareq Mainul Islam Bhuiyan passed the order as police brought Mohsin, also a TV presenter, before him along with the remand plea, two days after plainclothesmen arrested him from the yard of a mosque in Mohammadpur area.
After viewing a video footage on the internet, where 35-year-old Mohsin called the slain priest an "apostate", police arrested him.
Mohsin has alleged links with the group, police said adding, the same extremist group had killed a blogger last year for being an "atheist".
Farooqui, also the chief cleric of the Supreme Court mosque, was killed on August 27 by a group of assailants who stormed into his rented house at Razabazar area here and slaughtered him, keeping the family members locked in a room.
In his lectures, he visibly upheld the spiritual and Sufi thoughts referring to the Muslim saints in Indian sub-continent and elsewhere while opposing the Saudi-style Wahabi or Salafi Islamists.
Police had earlier said they suspected the murder to be a sequel of his disputes with the religious hardliners or Wahabis.
Following the murder, the Muslim-majority Bangladesh witnessed a series of protests, including nation-wide general strikes, demanding stern punitive actions against the assailants.