BNP secretary general Mirza Fakhrul Islam Alamgir has demanded immediate release of the arrested leaders and activists of the party's Sirajganj unit.
Speaking at a press conference at the BNP chairperson's Gulshan office in Dhaka, he also urged the authorities to drop the four "false" cases filed against party men over Thursday's Awami League-BNP clash.
Blaming the ruling party for the clash – that left at least 20 people injured – mostly BNP supporters, he said: "Our rally in Sirajganj for Khaleda Zia's treatment abroad was attacked by local Awami League, Chhatra League and Jubo League leaders and activists.
"They were taking preparations for the last two to three days just to sabotage our movement. They had weapons stockpiled to attack our people that day."
On Thursday, BNP called a meeting at Islamia College ground in the town demanding its chairperson's release and her treatment abroad.
A clash ensued between Awami League and BNP activists at one stage of the meeting, leaving over 100 people from both sides injured.
Over 700 BNP, Chhatra Dal and Jubo Dal activists were sued the following day.