Popular travel website Booking.com has warned customers that their personal information including booking details and names may have been accessed by an "unauthorised third party".
Booking.com is one of the largest digital travel companies globally, with more than 28 million accommodation listings worldwide.
The company sent emails to some of its Australian customers early this morning over what it described as "suspicious activity".
READ MORE: 'Becoming more plausible': Recession warning if Iran war rages on
"We're writing to inform you that unauthorised third parties may have been able to access certain booking information associated with your reservation," the email reads.
"We recently noticied suspicious activity affecting a number of reservations and we immediately took action to contain the issue."
The information accessed could include booking details and names, emails, addresses, phone numbers associated with the booking and "anything that you may have shared with the accommodation".
Booking.com has issued new PIN and reservation numbers to customers it believes have been affected by the data breach.
"The security of your personal information is our utmost priority," the Booking.com email said.
"We will continue to enhance and extend the robust security measures we have in place to secure your reservations with us."
Have you got a story? Contact reporter Lara Pearce at lp*****@******om.au
It also advised customers to take extra security precautions, such as installing antivirus software and being vigilant about clicking on any links sent from Booking.com or their accommodation provider.
Booking.com has been contacted for comment.
NEVER MISS A STORY: Get your breaking news and exclusive stories first by following us across all platforms.
- Download the 9NEWS App here via Apple and Google Play
- Make 9News your preferred source on Google by ticking this box here
- Sign up to our breaking newsletter here