The Australian reported that thousands of credit card details of customers of Australian banks are accessible through an unidentified blogging site. The site includes Visa, MasterCard and American Express numbers, including expiry dates, together with home addresses, phone numbers and email addresses.
Victoria Police are investigating.
A number of the records appeared to have been taken from a holiday accommodation database, the newspaper reported, with entries such as "Ensuite Villa, 2br" included alongside cardholders' details.
Others were from a courier organisation, including detailed delivery instructions for packages if the cardholder was not at home.