A Citibank spokeswoman, Maria Mendler, confirmed that the problem, believed to be caused by a fault in the software, began at approximately 5pm on Tuesday but was supposedly fixed later the same evening. Intermittent problems, however, have continued to hamper the machines, and technicians are still trying to determine the cause.
Citibank has around 1,300 ATMs in New York and another 700 machines around the US. Customers trying to use them discovered text messages saying they were out of service.
Mendler said that Citibank would refund service charges for customers who were forced to use fee-based ATMs owned by other banks.