The Health Service Executive in Ireland has closed down its IT systems after being targeted in what it said was a “significant ransomware attack”.
The HSE said it had temporarily shut down its systems as a “precaution”.
It said Covid-19 vaccination appointments were not affected by the incident.
“There is a significant ransomware attack on the HSE IT systems,” it said on Twitter.
“We have taken the precaution of shutting down all our IT systems in order to protect them from this attack and to allow us fully assess the situation with our own security partners.”
The HSE added: “We apologise for inconvenience caused to patients and to the public and will give further information as it becomes available.”
"Vaccinations not effected (sic) are going ahead as planned.”
The Rotunda maternity hospital in Dublin has been forced to cancel many routine appointments due to the IT issues.
It described the situation as a “critical emergency”.
“Due to a serious IT issue all outpatient visits are cancelled today – unless you are at 36 weeks pregnant or later,” the hospital tweeted.
It said all gynaecological clinics had been cancelled on Friday.
In a tweet, the hospital added: “If you have any urgent concerns please attend as normal.”