Authorities in the United States and overseas arrested 24 people Tuesday in a crackdown on Internet credit card fraud after an extensive undercover operation.


Two individuals were arrested in New York, nine elsewhere in the United States and 13 in a dozen other countries, according to a spokeswoman for the Federal Bureau of Investigation.


“We put a major dent in cybercrime,” she said. “This is an unprecedented operation.”


In the sting, which they called Operation Card Shop, undercover investigators created an online bazaar to catch buyers and sellers of stolen credit card data and other private financial information. They also aimed at people who produce the physical credit cards that are then used to buy merchandise.


Credit card theft has exploded in recent years, with major banks and credit card transaction processors finding themselves under assault from increasingly sophisticated cybercriminals.


Some of the most sophisticated hackers originated in Eastern Europe, but more recently have been found linked to criminal organizations around the world.


“From New York to Norway and Japan to Australia, Operation Card Shop targeted sophisticated, highly organized cyber criminals involved in buying and selling stolen identities, exploited credit cards, counterfeit documents and sophisticated hacking tools,” Janice K. Fedarcyk, assistant director in charge the F.B.I.’s New York field office, said in a statement.


She said the arrests would cause “significant disruption to the underground economy.”


The overall number of arrests had been reported earlier by the F.B.I. as 26.


Federal officials maintained that the operation prevented potential losses of more than $200 million. Credit card providers were notified of more than 400,000 compromised credit and debit cards, the officials said.


The online bazaar, or forum, one law enforcement official said, was “like a restricted eBay,” open only to people who had a reputation and who had been vouched for by someone on the site. Available in the forum were credit card information, other personal information, bank accounts, hacking tips, malware, spyware and access to stolen goods, like iPads and iPhones, the official said.


According to the United States attorney’s office in New York, the 11 arrested in this country bragged screen names like “JoshTheGod,” “IwearaMAGNUM,” “Cubby” and “OxideDox.”


“The coordinated law enforcement actions taken by an unprecedented number of countries around the world today demonstrate that hackers and fraudsters cannot count on being able to prowl the Internet in anonymity and with impunity, even across national boundaries,” said Preet Bharara, United States attorney for the Southern District of New York.