Security expert Brian Krebs reported that US banks had identified a pattern of fraudulent transactions involving accounts that had been used at a Trump Hotel Collection property.
The attack appeared to date back to February, he said.
The company said it was carrying out a “thorough investigation”.
“Like virtually every other company these days, we have been alerted to potential suspicious credit card activity and are in the midst of a thorough investigation to determine whether it involves any of our properties.
“We are committed to safeguarding all guests’ personal information and will continue to do so vigilantly,” the Trump Organization executive vice-president Eric Trump said.
In a blogpost published on July 1, Brian Krebs – a former Washington Post journalist – cited data from unnamed sources at several US banks suggesting a pattern of bank accounts being involved in suspicious transactions.
What each of the cases reportedly had in common was that the associated credit and debit cards had all previously been used at Trump hotels.
Brian Krebs reported that at least five different locations were involved: Chicago; Honolulu; Las Vegas; Los Angeles; Miami; and New York.
The claims brought concerns about the security of US credit cards to the fore. Many people in the US still swipe their cards and verify their identities with their signatures, while other countries have moved on to chip-and-pin.
If the fears were confirmed, the Trump Organization would become the latest in a series of US companies to be the victim of a credit and debit card breach.
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