The company's dealer network remains up and running, but "remedial works" continue and an emergency call centre has been set up to handle customer enquiries, including the Takata recall.

"At this stage, we do not believe that customer or employee data has been compromised," the company said in a statement on Friday.

The car marker has notified Australian government agencies, while its IT department works with international cyber-security experts to get the system back on track.

The company has no details about the origin of the attack after it became aware of the attempted hack on Tuesday morning, the statement says.

The company apologised for any inconvenience to customers.

It comes after reports hackers broke into the medical files at Melbourne Heart Group, a tenant at the Cabrini Hospital, and demanded a ransom after scrambling the data of about 15,000 patients.

The Melbourne Heart Group confirmed it had been unable to access patient data for weeks, but a spokeswoman said they had been assured that "no patient's privacy has been compromised in any way".

Australian Associated Press