Private data for more than 90,000 customers of Citigroup's Japanese credit-cards subsidiary has been stolen and unlawfully resold, the company said on Friday.

"Citi Cards Japan, Inc. (CCJ) has come to know that certain personal information of 92,408 customers has allegedly been obtained and sold to a third party illegally," the company said in a statement.

The compromised data includes account numbers, names, addresses and dates of birth but does not include PIN numbers or security codes for the affected cards, the Citigroup subsidiary said.

"While the risk of fraud is minimal due to the absence of security information, CCJ has placed internal fraud alerts and enhanced monitoring on all accounts identified," it said.

"No unusual or suspicious credit cards transactions relating to these customers have been detected at this point."