Prey Sar prison inmates involved in an alleged drug-trafficking network revealed by police last week likely took advantage of a loosening of safeguards designed to block mobile phone use, prison officials said yesterday.

Military police on Thursday reported the seizure of 13 kilograms of meth in powdered and tablet (yama) form, arresting one trafficker on the outside and five more – all Prey Sar convicts – who were allegedly managing the network from within.

A Prey Sar guard speaking on condition of anonymity yesterday said that while prisoners can make calls through the prison’s phone, all such calls require the punching in of a prisoner identification number and are recorded automatically.

“There are two phones in a room . . . controllers listen to their calls. If something is unusual, they cut off [the line]. But not all calls are listened to because there are many prisoners,” he said.

A far more likely source of communication, he said, is the banned, yet widespread, use of mobile phones inside the prison.

Although the Ministry of Interior installed a jammer in 2014 to combat the practice, it was subsequently moved after complaints from neighbours.

“The jammer used to be installed high above the roof, which affected the phone signal for the residents living around [Prey Sar],” he said.

After receiving the complaints, officials reinstalled the jammer lower, he said, allowing “some prisoners to use earphones to connect to the mobile phone, making it an antenna. They lift [the phone] up. In doing so, there is one or two signal bars at some points,” a practice, he said, prison guards have observed repeatedly.

Sorn Keo, a spokesperson for the Interior Ministry’s General Department of Prisons, acknowledged that prison guards see prisoners use phones often. The devices, he said, are usually brought in as parts and assembled at the moment of usage.

“Their phones are not like our phones. SIM cards and other parts are kept separately. When it is time [to use them], they combine them together. It doesn’t look like a phone. It is something invented,” Keo said, admitting that some prison officials would, of necessity, be abetting these activities.

What’s more, Keo continued, because the jammer is dependent on the state’s electrical grid, whenever there is a power outage, Prey Sar has full mobile service, creating a prime opportunity for prisoners to make calls.

According to the same prison guard, blackouts can occur four to five times per month, lasting 10 to 30 minutes.

While it is illegal for prisoners anywhere in the Kingdom to use cell phones, several provincial prison directors told the Post yesterday that to their knowledge, only Prey Sar possesses a jammer.

As to whether measures will be taken by the department to address these apparent security flaws, Keo said that for now he is waiting on direction from the ministry’s leadership.

Calls to the Ministry of Interior spokesman went unanswered yesterday.

Kea Sovanna, a former director of Trapaing Plong Prison in Tbong Khmum province now working at the Prison Department, yesterday recommended more rigorous security checks for both inmates and prison officials.

“Check both officials and prisoners regularly and every time. If the checking is applied only on one side, the phones will still be brought in, so all of them have to be checked.”