Four Mexican immigrants have been charged with possessing phony ID documents in the latest move by officials to crack down on the notorious fake-document market in Adams Morgan.

The men were indicted last week by a grand jury of the U.S. District Court for the District of Columbia. They face sentences of up to 10 years each if convicted, said Channing Phillips, a court spokesman.

The indictments were a result of Operation Card Shark, an effort by U.S. Immigration and Customs Enforcement to break up the rings that hawk phony Social Security and U.S. residency cards along Columbia Road NW.

The operation has resulted in the closure of six phony-document mills and the seizure of about 9,500 fake IDs, officials said. Including the latest arrests, 102 immigrants have been apprehended since the operation began three years ago, and 41 have been prosecuted, the agency said. Still, vendors continue to offer the fake IDs in Adams Morgan, a historically Latino area.

"It's a continuing problem, so we are continuing keeping the pressure on the area, to disrupt the trade," said Allan Doody, special agent in charge of the local immigration enforcement office.

He said authorities were seeking to file criminal charges against vendors rather than simply deport them, because it is "a bigger deterrent." The Mexicans were detained in May for being in the country illegally, officials said.

According to the indictment, Jose Luis Contreras-Macedas, 24, his brother Josue Contreras-Macedas, 21, and David Mora-Gil, 22, possessed phony Social Security cards, and the fourth man, Allan Joseph Vargas-Alvarez, 20, had a fake border-crossing card. Officials alleged that the men, all District residents, were street vendors of phony documents.

The men were also charged with aggravated identity theft, which could add two years to their sentences if they are convicted, Phillips said. Vargas-Alvarez faces an additional charge of re-entering the country illegally after being deported, which carries a two-year sentence.

The men have pleaded not guilty and are being held without bond, said Phillips.

U.S. Attorney Kenneth L. Wainstein said the crackdown is crucial because "false identification documents can be used as a means to all sorts of criminal ends, ranging from petty scams to large-scale fraud to terrorism. It is critically important that we curb the proliferation and reduce the availability of these documents, particularly in the Adams Morgan area, which has historically been a hub for their production and distribution."

The fake-document sales have occurred for years along Columbia Road despite occasional crackdowns. Officials say the informal market thrives because of the ease of making fraudulent IDs and because of heavy demand from illegal immigrants who use them to get jobs. But after the Sept. 11, 2001, attacks, officials became increasingly concerned that the market could be exploited by terrorists.

D.C. Council member Jim Graham (D-Ward 1), whose ward includes Adams Morgan, said the continued pressure by federal authorities seemed to be making a difference.

"This problem is not a five-yard dash. This is a long-distance run," he said. "But every time a federal action [occurs] it improves it. So today, compared to two years ago . . . [the trade] is now far more sporadic, there are fewer people [selling], there are fewer document mills."

However, he said, "If we don't keep the pressure on, it will go back to the way it was."