“The threats came over phone and in letters,” said a letter signed by Inspector General (IG) of Prisons Brig Gen AKM Mustafa Kamal Pasha on Sunday.
The letter directed all the prisons in the country to remain on high alert and issued an 18-point instruction to beef up security there.
The instructions include formation of a striking force consisting of a deputy jailer and keeping a chief jail guard and five jail guards in each prison ready to prevent any possible attack.
The striking force will monitor the movements of all the inmates, especially the militants and others accused of sensitive cases like those of the Border Guard Bangladesh (BGB).
At the entrances of the jails, prisons guards were asked to wear bullet-proof jackets and helmets and use metal detectors to check visitors.
The IG directed them to use armed sentries and ensure the security of weapons and arsenals and monitoring of CCTV footage persistently.
He also instructed them to arrange necessary measures so that arms and ammunition can be procured quickly from the prison arsenal at any required moment.
The boundary walls around prisons should be secured in addition to checking the alarm systems and keeping those ready.
The police authorities should be informed about their incidents in prisons where militants are kept as inmates, while the jail authorities have been asked to maintain constant contact with law enforcers, the letter added.