Prosecutors said only two of the defendants are in custody. The rest are fugitives.

An indictment unsealed in U.S. District Court in Manhattan accused six of the defendants of aiding Colombia's rebel army, the Revolutionary Armed Forces of Colombia, or FARC, which the U.S. government considers a terrorist organization.

The indictment says the FARC's leadership has ordered members to kidnap and kill Americans and attack U.S. interests to dissuade American authorities from helping Colombia disrupt cocaine manufacturing and distribution.

A separate indictment returned last May charged nine of the 12 with kidnapping a U.S. citizen in April 2008 in the Costa del Este neighborhood of Panama City, Panama. The victim, who was not identified in court papers, was released in February after his family paid ransom.

According to the indictment, one defendant told a member of the kidnapping victim's family in Miami during a July 2, 2008 telephone call that the family would never see him again unless the full ransom was paid. The indictment did not specify the ransom amount.

Three defendants are accused of guarding the victim while he was held, while others are accused of negotiating the ransom and physically detaining the victim.

The victim's family moved money between September 2008 and last December from Miami to Panama City, where it was eventually withdrawn from a bank, the indictment said.

The kidnapping victim has since returned to the United States, the indictment said.

U.S. Attorney Preet Bharara said in a statement that the defendants belonged to the "57th Front," one of the FARC's most violent elements.

"This group of guerrillas kidnapped a United States citizen, procured weapons and explosives and trafficked cocaine to fuel the FARC's terrorist activities," he said. "The charges unsealed today mark another important step in our efforts to combat international narco-terrorism."

Michele M. Leonhart, the Drug Enforcement Administration's acting administrator, said the agency and its partners in Panama and Colombia will pursue the 57th Front until its members have surrendered or been captured.

Bharara said the Colombian Navy, the Colombian National Police, the Colombia Attorney General's Office and the Panamanian National Police assisted in the investigation.