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. Last Updated: 07/27/2016

Citibank Cards Blocked in Russia, Britain and Canada

NEW YORK — Citibank said Wednesday that it had blocked the use of some of its PIN-based debit cards after detecting fraudulent cash withdrawals in three countries.

The bank, the retail arm of Citigroup, the largest U.S. financial institution, said the debit-card information apparently was obtained by thieves in "a third-party business' information breach" last year.

Citibank did not name the merchant or processing firm, but industry officials familiar with the case said the breach occurred in the United States.

Citibank said it began monitoring affected accounts after the breach, "and in mid-February, we detected several hundred fraudulent cash withdrawals in three countries."

The industry officials, who spoke on condition of anonymity because of the sensitivity of the issue, said the three countries were Britain, Canada and Russia.

The bank said it blocked transactions on cards that may have been compromised in the breach after the fraud was detected. Debit cards often require the use of PINs, or personal identification numbers, for security.

"We are in the process of contacting affected customers individually, and can provide new cards to customers affected by this third-party breach anywhere in the world they may be traveling," Citibank said in a statement.