Hackers have stolen data on more than 600,000 Domino's Pizza customers in Belgium and France, the company said, and an anonymous Twitter user threatened to publish the data unless Domino's 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 on Monday.
He said he did not know if the stolen passwords had been encrypted.
A Tweet directed at Domino's customers through an account of somebody listed as "Rex Mundi" said hackers would publish the customer data on the Internet unless the company pays 30,000 euros ($40,800), according to an article in The Telegraph.
The Rex Mundi account was later suspended.
"Earlier this week, we hacked our way into the servers of Domino's Pizza France and Belgium, who happen to share the same vulnerable database. And boy, did we find some juicy stuff in there!" the post read.
Brandon said he was not familiar with the ransom demands, but that the company would not be making any such payment.
Domino's Vice President of Communications Tim McIntyre said the hacking was "isolated" to independent franchise markets of Belgium and France, where the company's online ordering system did not collect credit card orders, so no financial data had been taken.
"This does not affect any market outside of France and Belgium," he said via email. "The site has been secured."
Domino's has some 11,000 stores worldwide, including 229 in France, 24 in Belgium and about 5,000 in the United States.
News of the hack came on the same day that Domino's announced an app in the U.S. that lets people order pizzas with the help of a voice-activated digital assistant named Dom.