On Thursday midnight, a caller identifying himself as a PBCP operative threatened to blow up the Khulna Metropolitan Police (KMP) Headquarters over cellphone to take revenge for the recent killings of the PBCP men by DB police on the pretext of crossfire incidents.

The DB police arrested Shafiqul Islam, 25, from Morolpara under Phultala upazila of Khulna on Friday afternoon in this connection and seized from his possession the cellphone from which the threat call was made.

During interrogation, Shafiqul told the police that he had given the cellphone to a man named Shohag to sell off the set, but Shohag returned the cellphone a few days ago saying that he could not find a buyer.

Police suspect Shohag to be another cadre of PBCP and a close associate of Mukul Bhuiyan, who was killed in 'crossfire' on March 18 in the city. The seized cellphone contains contact numbers of many other outlaws, police said.

Police could not arrest Shohag up to 4:30pm yesterday.

Following the threat, KMP police and Rapid Action Battalion (Rab) have been asked to remain on high alert.

The law enforcers are also raiding different areas in the city to nab the criminals.