More Medibank customers may have had their information stolen after the health insurance provider revealed that the cyber attack on the company was wider than originally thought.

Here is what we know and what Medibank has said to do if you are a customer.

What was today's update?

On Tuesday morning, Medibank confirmed that data from its main brand has also now believed to have been compromised.

Medibank said it had come to this conclusion after being sent customer data by criminals that included data from all three entities.

Previously, Medibank said the breach only affected customers of its subsidiary, ahm, and data collected about international students studying in Australia who use Medibank under its OSHC service.

What happened last week?

• Medibank was hit by a cyber attack on October 13 but at the time the company said there was no evidence that sensitive data had been accessed
• Last Wednesday, it issued a statement saying it received a message from a group claiming to be hackers
• The company halted trading on the share market as a result
• Cyber Security Minister Clare O'Neil said the attack has been referred to the Australian Federal Police
• Medibank is also working with the Australian Cyber Security Agency and the Australian Signals Directorate
• Last Thursday, Medibank confirmed a criminal has provided the company with a sample of 100 records, which it believes are from its systems
• The company expects that more people will be impacted as investigations continue

What should Medibank customers do?

All Medibank and ahm customers have been urged to contact the company's cyber response hotlines by phone (for ahm customers 13 42 46 and for Medibank customers 13 23 31) or through an information page on the firm's website.

Medibank has initiated a dedicated cybercrime customer support package to respond to the breach which includes:

• A hardship package to provide financial support for customers who are in a uniquely vulnerable position as a result of this crime, who will be supported on an individual basis
• Access to Medibank's mental health and wellbeing support line for all customers, including ahm customers
• Access to specialist identity protection advice and resources from IDCARE
• Free identity monitoring services for customers who have had their primary ID compromised
• Reimbursement of fees for re-issue of identity documents that have been fully compromised in this crime

The company has also established specialised teams to help customers who receive scam threats.

Medibank customers should send any suspicious emails or texts to scaminvestigations@medibank.com.au, while ahm customers should email scaminvestigations@ahm.com.au.

Medibank has reminded customers to stay vigilant for possible scams and said it will never contact customers requesting passwords or other sensitive information.

Customers can also speak to Medibank's qualified mental health professionals 24/7 over the phone for advice or support around mental health or wellbeing (1800 644 325).