BOGOTA, Oct 25 (Reuters) - U.S. authorities have asked Colombia to extradite a paramilitary chief wanted on drug charges after the government said he violated a peace deal with President Alvaro Uribe, the foreign ministry said on Thursday.

Carlos Mario Jimenez, known as Macaco, was the first outlawed militia commander to lose benefits offered for disarming and ending illegal activities after years of atrocities committed in the name of fighting left-wing guerrillas.

Colombian authorities in August said Jimenez would face extradition after charging the paramilitary chief had kept on organizing drug trafficking from his jail cell in breach of the accord that had offered short sentences for surrender.

"The formal request was received from the U.S. embassy for the extradition of Carlos Mario Jimenez," the foreign ministry said in a statement.

The request must be approved by the Supreme Court and by Uribe's government, it said.

The extradition demand comes as Uribe, a Washington ally, fends off a scandal tying several lawmakers close to him to the paramilitaries, who are accused of some of the worst atrocities in Colombia's four-decade conflict.

Uribe says the arrests of lawmakers helps root out lingering paramilitary influence. But U.S. Democrats in Congress debating a free trade deal for Colombia want to see more success in curbing the "para" commanders and in stopping rights abuses.

The president is popular for his security crackdown on the rebels and for the paramilitary disarmament, which has helped reduce violence and kidnappings. Guerrillas are still fighting in remote areas.

Under the peace deal, commanders surrendered their weapons and demobilized more than 31,000 fighters in exchange for short jail terms provided that they were not involved in illegal activities, compensated victims and confessed to crimes.

Some had U.S. extradition warrants frozen as part of the agreement.

But rights groups complain the jailed warlords have kept crime gangs intact and have been slow to live up to their end of the deal. The government acknowledges some paramilitaries have rearmed into gangs tied to Colombia's cocaine trade.

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