One of the inmates who had set up the computers later described how he had used components from other PCs that were part of a computer waste recycling programme.

He then plugged his machine into an internet connection device in the prison, according to the Inspector General's report.

"And then... bam, I'm on the network," he told investigators.

A trove of data was discovered on the machines, including records of passes being issued for inmates so they could access various parts of the prison.

Forensic analysis of the hard drives also found pornography, articles about making drugs, explosives and credit cards.

One IT employee was found to have breached inventory and crime scene protection policies.

"We will thoroughly review the reports and take any additional steps necessary to prevent these types of things from happening again," the Ohio Department of Rehabilitation and Correction said in a statement.

"It is of critical importance that we provide necessary safeguards in regards to the use of technology while still providing opportunities for offenders to participate in meaningful and rehabilitative programming."