WASHINGTON — Federal prosecutors alleged that members of an elaborate hacking ring broke into debit-card systems and stole $9 million from ATMs in hundreds of cities worldwide.

Prosecutors in Atlanta announced indictments against eight members of the alleged ring, from eastern European countries, Tuesday in what is believed to be among the most brazen and damaging electronic bank heists to date.

The alleged hackers cracked a computer system at RBS Worldpay Inc., the U.S. payment processing division of Royal Bank of Scotland Group PLC, and cloned prepaid ATM cards, which thieves then used to withdraw cash from 2,100 ATMs from 280 cities around the world.

The heist took place in November of last year and RBS Worldpay announced the breach in December, in which data of 1.5 million cardholders was compromised.

The data breach affected the company's system for issuing pre-paid debit cards, including gift cards and payroll cards. But the company acknowledged at the time that 1.1 million social security numbers may also have been lost.