(Adds color, victim and U.S. ambassador comments)

By Hugh Bronstein

BOGOTA, May 7 (Reuters) - Colombia extradited Carlos "Macaco" Jimenez to the United States on Wednesday, making him the first right-wing paramilitary boss to face U.S. justice for drug trafficking.

The move threatens to increase tension with other former paramilitary chiefs who are jailed in Colombia but are suspected of continuing to command cocaine-smuggling and extortion organizations from behind bars.

The militias, formed in the 1980s to fight left-wing guerrillas, have demobilized over the past four years under a peace deal in which they turned over their guns in exchange for benefits including reduced prison sentences and an agreement that they would not be extradited.

But Colombia accused Jimenez of violating the terms of the peace accord by ordering crimes from his jail cell.

His extradition came as Democrats in the U.S. Congress demand that conservative President Alvaro Uribe do more to control paramilitary influence over criminal gangs before the lawmakers can back a U.S.-Colombia free trade deal.

Television news reports showed the bearded and bespectacled Jimenez getting ready for his early-morning flight to Washington, a bulletproof vest covering his cream-colored sweater.

"This was a smart move by Uribe," Bogota-based security analyst Pablo Casas said of Jimenez's extradition. "It sends a message to emerging criminal groups, commanded by former paramilitaries, that the government will be tough on them. It also shows U.S. Democrats that Uribe is serious about confronting the paramilitaries."

They were first organized as private militias by drug-smugglers, cattle ranchers and other rich Colombians trying to protect themselves from land grabs and kidnappings by rebels who are still fighting the state.

MASSACRES AND DISAPPEARANCES

Funded by the country's multibillion-dollar cocaine trade, the "paras" soon grew more powerful than their original benefactors. They terrorized this Andean country in the name of fighting Marxist insurgents, using massacres and disappearances to intimidate rural populations long neglected by the state.

Human rights groups have criticized the peace deal for being too lenient with former militia leaders, but not all rights activists welcomed Wednesday's extradition.

"What are we going to learn about severe human rights violations that occurred in Colombia now that 'Macaco' has been extradited?" said Lisa Haugaard, head of the Latin America Working Group, a Washington-based human rights organization.

"Extradition can be a useful tool, but we need to know about the full scope of the horror that occurred in Colombia," she said. "We need to know who the 'paras' worked with and where the bodies are buried."

U.S. ambassador in Bogota William Brownfield told reporters that Jimenez's victims will be heard during his U.S. trial.

But Amparo Cano, family member of one of the thousands of people who disappeared in the northern Colombia area once controlled by Jimenez, said victims' families had hoped that he would reveal more information before leaving the country.

"We are being left in the dark," she told reporters.

Uribe's international standing has been hurt by a scandal in which dozens of his political allies are being investigated for suspected illegal dealings with paramilitary groups.

But he remains popular at home for cutting crime and sparking investment with his U.S.-backed security policies. (Reporting by Hugh Bronstein; Editing by Vicki Allen)

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