Over 10 million subscriber identity module (SIM) cards not registered by Bangladesh's six mobile phone operators are being misused for criminal activities and fomenting Islamist militancy, police said.
The operators have at least 30 million subscribers of whom 35 percent use unregistered SIM cards, The New Nation newspaper reported.
"Each criminal or terrorist keeps 400 to 500 unregistered SIM cards at his disposal. A SIM card is destroyed after using it only once," it quoted unnamed sources as saying.
Militancy by Islamist extremists has posed a serious challenge to the authorities, particularly since 9/11 Al Qaeda attack in New York. Four outfits were banned, but another 25 bodies are active, regrouping under different names.
Media reports have indicated widespread use of cellphones by these outfits with their counterparts in India and Pakistan.
The detective branch of the Dhaka Metropolitan Police has a cyber crime unit. It is capable of detecting only five to six illegal SIM card users per month.
Absence of strict laws and poor monitoring stands in the way of punishing the cyber criminals and those issuing threat to rich people for money, police sources said.
Hardened criminals use unauthorised SIM cards in their cell phones to demand money from the targeted people and issue death threat for non-compliance.
Businessmen, contractors and wealthy people are their main targets, the newspaper said.
As the criminals use unregistered SIM cards, it becomes very difficult for the law enforcing agencies to detect their whereabouts.
The previous caretaker government (2007-08) took steps for the SIM card registration and framed rules for this purpose. But an unspecified number of people at that time used fake documents for registration of SIM cards.
Cyber crime expert Tanvir Ahmed told the New Nation that if the phone operators strictly follow the rules for selling SIM cards, the use of unregistered SIM cards would decrease substantially.