The Irish Prison Service has confirmed that 139 prisoners had their telephone conversations with solicitors recorded while in custody.
The Prison Service said inmates are given a confidential phone line for conversations with a named solicitor.
However, because some inmates had more than one solicitor representing them but only one named with the prison service, the other conversations were inadvertently recorded.
Earlier, the Taoiseach Enda Kenny said 84 inmates had their conversations recorded.
In a statement this evening, the Prison Service said a further 55 prisoners had been identified as previously having a second solicitor listed on the system.
The Prison Service said the information was revealed following engagement between its IT Section and the prisoner phone service provider.
The Prison Service informed the Government of the issue today and is now compiling a report for the Minister for Justice.
Mr Kenny said the Prison Service took steps to rectify it immediately when they became aware of it.
He said he had asked the Minister for Justice for a report on how this had happened.
RTÉ News understands that the issue of prisoners' calls being recorded is being examined in the context of the Commission of Investigation into the recordings at garda stations.
It is believed it is likely to be included in the commission's terms of reference.