The authorities at Rajai Shahr prison in Karaj installed at least two mobile phone jamming devices in the prison yesterday.
The devices, which are illegal to use in many countries, were installed in Ward 1 and Ward 4 of the prison. There is a controversy surrounding the potential health risks posed the devices, which operate by emitting radio waves on a similar frequency used by mobile phones.
It is not known whether the devices used in the prison comply with international regulations on electromagnetic radiation, and initial reports suggest that the devices are already affecting the health of the prisoners.
The Human Rights Activists News Agency reported that since the devices were installed, prisoners had encountered side effects such as headaches, dizziness and dryness of the mouth.
Sunni political prisoners are held in Hall 10 which is located in Ward 4, one of the wards in which the devices were installed.