Hefajat-e Islam has called countrywide daylong shutdown for May 12 protesting Monday crackdown on its leaders and workers.
Meanwhile, a Dhaka court on Tuesday placed Hefajat Secretary General Junaid Babunagari on a nine-day remand in a sub-inspector murder case.
Speaking at a press briefing at Hathazari on Tuesday afternoon, a Hefajat leader also extended their support to the May 8, 9 hartal called by the BNP-led 18-party opposition alliance.
Hefajat Cultural Secretary Ashraf Ali Nizampuri also threatened of tougher agitation programmes of their leaders and activists are not released by May 12.
Metropolitan Magistrate Tareque Mainul Islam Bhuiyan passed the order after police produced Babunagari before him with a 10- day remand prayer in the case.
Sheikh Mofizur Rahman, a sub-inspector of Motijheel Police Station and investigation officer of the case, sought the remand.
Police picked up Babunagari near the Dhakeshwari Temple on Monday evening, minutes after Hefajat chief Shafi Ameer Shah Ahmad Shafi left Dhaka for Chittagong to avoid arrest after thousands of his followers resorted to brute violence in downtown Dhaka on Sunday, causing widespread damage.