The Department of Health was subjected to a further cyber attack similar to the ransomware attack on the HSE last week.
The Department shut down its systems as a precaution following the attack, which occurred on Thursday, and is in the process of safely restoring data.
Authorities are attempting to establish the extent of the breach which is similar to Friday's attack on the health service.
The National Cyber Security Centre, along with Gardaí and the Defense Forces, is liaising with the Department of Health on this ransomware attack.
Investigations are taking place to establish whether the same criminal gang believed to be behind the attack the HSE is involved.
It is not yet clear the extent of the breach at the Department of Health and what information has been encrypted.
In a statement, the Department confirmed it is continuing to assess the impact of the attack and is working to respond with the relevant authorities.
Meanwhile, the HSE is in the process of contacting thousands of patients to reschedule appointments following Friday's cyber attack.
All outpatient and radiology services are impacted, however, chemotherapy and dialysis services are continuing as normal.
— HSE Ireland (@HSELive) May 16, 2021
COVID-19 vaccination appointments are going ahead as normal but there are delays to the testing and tracing programme.
The health service said it is prioritising emergency services over the coming days, with staff told to “protect unscheduled and urgent care”.
Anne O'Connor, Chief Operations Officer at the HSE, told On The Record with Gavan Reilly that work has begun on rebuilding IT systems but the process will be slow.
"It's been an extraordinary few days for us, the reality is there's not much back up and running," she said.
"Where we're at at the minute is we have between yesterday morning and this morning found that we do have some clean back-up data available to rebuild our servers from.
"However, we have thousands upon thousands of virtual servers so each server is going to have to be rebuilt and brought back up individually.
"So it's going to be a slow process, our system has been very significantly compromised across the board."
Earlier, Dr Denis McCauley, Chair of the IMO GP Committee and a GP in Donegal, explained that General Practices are "up and running" albeit with "certain caveats".
"Because of the situation in the hospitals, we've been asked to restrict certain routine diagnostic tests such as x-rays and bloods for the next few days," Dr McCauley said.
"The other issue is access to COVID assessments and COVID testing and vaccinations.
"If you have symptoms and you're worried you might have COVID, you should still contact your GP because he or she will be able to give you information about what to do."
As for other health concerns, he said: "I want to reassure people that if you are ill this week, your GP will look after you.
"But if somebody wants to come in and have their cholesterol checked or have an MOT or have an x-ray, there will be a two or three-day delay in that."