For the second time in a year, the Queens district attorney's office announced it has broken up a credit card fraud operation that had access to millions of dollars in credit lines.

Officials arrested eight of nine people they said were part of a Nigerian crime ring working underground in the New York City borough, but the alleged ring leader was still at large. The nine were indicted on multiple counts of theft and fraud.

In addition to the U.S. Postal Service and the Secret Service's West African task force, the district attorney's office worked with MasterCard, Visa, American Express, leading bank issuers, transaction processing companies, and credit bureaus to bust the ring.

Those indicted are accused of diverting mail to rented boxes in Queens, targeting workers at retail stores to gain access to cardholder information, and manufacturing false documents and fake credit cards.

The district attorney's office said it discovered equipment for the mass manufacture and distribution of fake credit cards, including magnetic tape, blank cards, change of address forms, holograms, cellular phones, and beepers.

Authorities said they also found forged Visa, MasterCard, American Express, and Discover cards numbering in the thousands, and personal documents on people from around the country, such as credit bureau reports, bank and brokerage documents, and medical records.

The indicted individuals are said to have bought electronic merchandise such as stereos, computers, and fax machines, which they sold on the underground market in Nigeria.

Richard A. Brown, the Queens district attorney, said the group's methods differed slightly from those of a group arrested last year in a similar Queens bust. In this instance, he said, the group relied on full credit bureau reports, rather than the abbreviated versions typically obtained for credit check purposes.

"This group had moved away from plastic, because they recognized the fact that plastic was more traceable," Mr. Brown said.

In the course of three weeks, the ring stole half a million dollars from the credit card accounts, the district attorney said, and it had access to credit lines totaling $20 million.

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