Hackers have stolen data on more than 600,000 Domino's Pizza Inc. customers in Belgium and France, the pizza delivery company said, and an anonymous Twitter user has threatened to publish the data unless the company pays a cash ransom.

Customer names, delivery addresses, phone numbers, email addresses and passwords were taken from a server used in an online ordering system that the company is in the process of replacing, Domino's spokesman Chris Brandon said Monday. He said he did not know if the stolen passwords had been encrypted.

A message directed at Domino's customers through the account of somebody listed as "Rex Mundi" said hackers would publish the customer data on the Internet unless the company pays €30,000 ($40,800), British newspaper The Telegraph said.