Sources said the arrested are not FIR-named persons.

Meanwhile, Md Amanullah, a cousin of slain chairman, filed a case on Friday night accusing 19 pro- Awami League (AL) leaders and activists.

Police said ABM Fazle Karim Chowdhury, AL MP from Chittagong - 6 (Raozan), was made the prime accused followed by Pourasava Chairman and former BCL leader Debashish Palit in the murder case.

"The AL MP, pourasava chairman and other AL men were implicated in the case to serve the political interest of a BNP high-up, and the case was lodged belatedly through a third person after failing to persuade the victim's wife and brothers," alleged a source.

Abu Taher, chairman of West Guzra and a known leader of BNP's Salahuddin Quader Chowdhury group, was shot dead by gunmen reportedly loyal to BNP's another group on Thursday evening.

Raozan BNP observed a dawn- to-dusk hartal yesterday protesting the killing.