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.
(Also see: Domino's Introduces a 'Siri' to Take Mobile Orders)
The Rex Mundi account was later suspended.
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.
© Thomson Reuters 2014
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