Washington - A Colombian rebel leader captured last year during the rescue of Ingrid Betancourt Friday pleaded not guilty to charges of drug trafficking in US federal court.

Gerardo Aguilar, also known as "Cesar" and a member of the leftist Revolutionary Armed Forces of Colombia (FARC ), arrived Thursday in the US in the custody of agents of the US Drug Enforcement Administration (DEA).

Also present in the courtroom was one of three Americans, Marc Gonsalves, who were among the 15 hostages released in a bold operation last year to free Betancourt, a one-time Colombian presidential candidate.

Prosecutor Eric Snyder attempted to include kidnapping in the narco-trafficking case.

But defence attorney Carmen Hernandez objected, noting that the extradition order granted by the Colombian Supreme Court specified that "Cesar" could only be tried in the United States for drug trafficking.

The kidnapping - a crime for which extradition had also been requested - happened on Colombian soil, and Aguilar should therefore face trial for that charge in Colombia, the Colombian court ordered.

"The subject must keep to drug trafficking, the decision of the jury must be on drug trafficking and all the issues of the kidnappings and the North American citizens have nothing to do directly with the accusation," she insisted.

Hernandez said she would try to prove that Aguilar was not involved in sending cocaine to the United States.

After the hearing, Gonsalves told journalists he wanted to see Aguilar in jail "for a long time."

Aguilar was arrested on July 2, 2008 in an undercover operation by the Colombian Army. The effort rescued Betancourt - the most high- profile hostage held by FARC - and three US defence contractors, as well as 11 Colombian military and police officers.

Along with "Cesar," the authorities arrested Alexander Farfan, alias "Gafas." However, a request for his extradition to be tried in the United States for kidnapping was denied by the Supreme Court.

In the rescue operation, undercover military agents made Aguilar and Farfan, who were in charge of guarding the hostages, believe they were part of a humanitarian commission to take the hostages to a different rebel camp. When the helicopter took off with the group, the two rebels were subdued by the soldiers.

The Colombian Supreme Court ruled that Aguilar was in charge "of supervising the manufacture and distribution of cocaine, over 1,000 kilogrammes that was imported into the United States."

In recent years, Bogota has extradited FARC leaders Ricardo Palmera, alias "Simon Trinidad," and Nayibe Rojas, alias "Sonia," to be tried for drug trafficking in the United States.(dpa)