Covid-19 was previously reported at the Midlands Prison in Portlaoise
A small number of prisoners have tested positive for Covid-19 at one of the country's jails where there has also been a staff outbreak.
The Irish Prison Service confirmed the outbreak at Wheatfield in Dublin on Monday, January 4.
"Following the confirmation last week of positive cases among staff in Wheatfield Prison, the Irish Prison Service can confirm that following the completion of the mass testing of all staff and prisoners in Wheatfield Prison, there have been additional positive Covid-19 staff cases detected.
"The Irish Prison Service can also confirm that 5 prisoners have also tested positive for Covid-19.
"The Irish Prison Service and Wheatfield Prison management have implemented a comprehensive contingency plan to prevent the spread of Covid-19 to the wider prison population.
"The Irish Prison Service is continuing to work closely with HSE/Public Health and arrangements are being made with the HSE for the re-testing of all prisoners and staff, later this week, in order to provide an assured response to the current outbreak in Wheatfield Prison. This will support a return to a more normal prison regime as soon as possible," said the statement.
The IPS said it continues to work closely with Public Health, HSE and contact tracing is still ongoing.
Wheatfield Prison is a closed, medium security place of detention for adult males and for sentenced 17-year-old juveniles. There were 507 prisoners in custody on January 31 this year.
This is not the first outbreak in an Irish jail. The Midlands Prison, Mountjoy and Limerick were all previously impacted.