NEWARK, N.J. — Eighteen people were charged in what may be one of the nation’s largest credit card fraud rings, a sprawling global scam that duped credit-rating agencies and used thousands of fake identities to steal at least $200 million, federal authorities said Tuesday.

The elaborate scheme involved improving fake cardholders’ credit scores, allowing the scammers to borrow more money that they never repaid, investigators said.

Paul Fishman, the U.S. attorney in Newark, described an intricate Jersey City-based con that began in 2007, operated in at least 28 states and wired money to Pakistan, India, the United Arab Emirates, Canada, Romania, China and Japan.

The group used at least 7,000 fake identities to obtain more than 25,000 credit cards, Fishman said. He said investigators documented $200 million in losses, but the figure could rise.

Participants in the scam set up more than 1,800 mailing addresses, creating fake utility bills and other documents to provide credit card companies with what appeared to be legitimate addresses, investigators said.

Once they obtained the cards, they started making small charges and paying off the cards to raise their credit limits, authorities said.

They then sent fake reports to credit-rating agencies, making it appear that cardholders had paid off debts, setting the stage for sterling credit ratings and high credit limits, investigators said.

Fishman said once the credit limits were raised, participants would take out a loan or max out the credit card and not repay the debts.

The group also created at least 80 sham businesses that accepted credit card payments, Fishman said. The group would run the fraudulently obtained credit cards through the machines, keeping the money, he said.

Three jewelry stores in Jersey City were closed Tuesday and their inventory seized, Fishman said. The stores are located within blocks of one another in a heavily Indian section of Jersey City.

Many of the defendants own property in New Jersey or New York and are U.S. citizens.