Hackers have “scrambled” patient files at a Melbourne heart specialist clinic in what was reportedly a ransom attempt.

The Australian Cyber Security Centre has confirmed it’s providing advice and assistance to the Melbourne Heart Group, which leases practice space from the Cabrini hospital in Malvern.

“As the matter is ongoing, it is not appropriate to comment further,” a spokesman from the centre said.

The Australian federal police is also involved in a joint investigation.

The Age reported the malware used to penetrate the unit’s security network is believed to be from North Korea or Russia, while the origin of the perpetrators has not been revealed.

A Melbourne Heart Group spokeswoman said the hackers had “scrambled the data”.

She declined to say whether the clinic had paid ransom money to the hackers or how many files had been compromised.

“I don’t want to make any further comment. We’re extremely busy and have got a lot of patients coming in,” she told the Guardian.

The clinic later released a statement saying in late January the Melbourne Heart Group experienced a cybersecurity incident in which its patient data was encrypted.

“This means that our patients’ information became inaccessible to anyone, including ourselves,” the statement said.

“We have been assured that no patient’s privacy has been compromised in any way.”

The clinic said it was working through this issue with its IT provider and hoped to resolve it soon.

“The health and wellbeing of our patients is always our primary concern. Their privacy is of the utmost importance to us,” the statement said.

“We are deeply sorry that this incident happened and encourage all our patients to contact our office so that we can keep them updated.”

Cabrini hospital clarified that data storage and other information systems in specialist suites were owned and managed by the specialists.

“No Cabrini data storage or patient-related systems or operations have been impacted or compromised by this incident and there has been no breach of hospital patient data,” the Cabrini Health chief executive, Dr Michael Walsh, said.