The private details of almost 200 patients being treated at a major Melbourne hospital may have been accessed by online criminals.
On Thursday, the Royal Women's Hospital notified 192 patients their data might have been compromised.
The hospital says it has not been hit by a cyberattack and the breach was sparked by a worker who sent details about the patients to their personal email account in a bid to co-ordinate appointments and treatment.
That email account was then accessed by cyber criminals.
The Royal Women's Hospital said it was investigating the attack and was keeping patients updated.
"We are taking this matter very seriously and apologise sincerely for any distress and inconvenience caused to affected patients," a spokeswoman said.
Medical records have not been accessed and the service's IT systems remained secure, she said.
The hospital has offered affected patients free counselling and help from cybersecurity experts.
