Officials searching the prison cell of jailed former opposition figure Meach Sovannara for a mobile phone Prime Minister Hun ordered them to seize did not find a handset, but they did come up with what they described as his communication channel to the outside: a television.

Prison department spokesman Sorn Keo said on Wednesday that officials do not believe Sovannara had a mobile phone or that prison officials colluded to provide one.

“He renovated the TV system to speak online to the outside,” Keo said, before admitting that officials “do not know how he connected it.”

Prime Minister Hun Sen scolded prison officials for allowing Sovannara to use a mobile phone while in prison in a speech Tuesday, accusing the inmate of politicking from behind bars and threatening to fire the prison chief. Sovannara, who is a dual US-Cambodian citizen, has been serving a 20-year prison sentence since 2015 for leading what the government characterised as an “insurrection” at Freedom Park.

Although illegal, use of mobile phones by inmates is widespread in Cambodia's prisons.

In 2014, Prey Sar prison officials set fire to more than 1,700 mobile phones confiscated from inmates over the previous three years and installed equipment to jam mobile phone signals. The equipment was removed after neighbours complained.

In 2016, five convicts of Prey Sar prison were arrested and accused of operating a large drug network from behind bars using cellphones. And just last year, investigators accused staff at Prey Veng prison of allowing an inmate to extort women who sent him sexually explicit photos and videos, discovering that he had several cellphones and a laptop while in prison.

Keo said prison officials had taken Sovannara’s TV and separated him from other inmates. He said no officials would be punished but that officials may discipline Sovannara for “violating internal regulations.”

“We will check [his punishment] more thoroughly,” Keo said.