In yet another black eye for the FBI, a security expert with the agency has been accused of selling top-secret information to the Mafia and others involved with criminal investigations.

James J. Hill, 51, is charged with obstruction of justice, conspiracy, and stealing and selling classified FBI documents.

As a security analyst in the FBI office in Las Vegas, Hill had access to informant identities and witness lists, the FBI said.

Hill, an Air Force veteran, was paid $25,000 for files from November 1999 until last week, according to a six-page complaint filed in U.S. District Court in New York. He was arrested Friday in Las Vegas after allegedly faxing classified information drawn from computer files to an FBI informant in New York.

A detention hearing was scheduled for Wednesday in Las Vegas.

The FBI spent Tuesday assessing the damage that could have been caused by the potential release of what the complaint refers to as "hundreds of different classified FBI records and documents pertaining to criminal cases and grand jury investigations."

According to the complaint, Hill had security clearances and access to national security data, confidential informant identities, witness lists and electronic surveillance information. An FBI official in New York said the case involves criminal files and not national security secrets.

The complaint, filed by Special Agent Demetrius Barkoukis, accuses Hill of selling classified FBI records relating to organized crime, white-collar investigations and international immigrant smuggling.

An unnamed informant, identified as a private investigator arrested Thursday, told the bureau he received the records from Hill. In one recent case, the informant said he sold them for $4,000 to a man in Oyster Bay, N.Y., who also has been indicted in the case, the complaint said.

Barkoukis also cited telephone records showing that Hill was in communication with people in Cuba and Mexico and said passport records showed Hill had traveled within the last year to Colombia.

Grant D. Ashley, Las Vegas' FBI special agent in charge, declined to provide further details because a criminal investigation is continuing.

The accusations against Hill follow a series of embarrassments for the FBI, including:

—  the arrest in February of counterintelligence agent Robert Hanssen, who is accused of spying for Moscow for 15 years;

— the announcement last month that more than 4,000 FBI documents had been withheld from lawyers for Oklahoma City bomber Timothy McVeigh;

—  the botched investigation last year of former Los Alamos scientist Wen Ho Lee.

The charges also come as a Senate Judiciary committee prepares for a hearing on the agency Wednesday and as the White House seeks a replacement for retiring FBI director Louis Freeh.

The Associated Press contributed to this report.