* Senator plans to contest ruling - lawyer
* FARC names new member of top body after commander killed
BOGOTA, Sept 27 (Reuters) - A leading Colombian left-wing senator has been dismissed and banned from public office for 18 years, accused of collaborating with the Andean nation&${esc.hash}39;s FARC rebels, the Inspector General said on Monday.
Once a powerful force that kidnapped and bombed at will, the Revolutionary Armed Forces of Colombia (FARC) has been driven back into remote mountains and jungles by Colombia&${esc.hash}39;s U.S.-backed military campaign.
Insurgents are now deeply engaged in cocaine trafficking.
Inspector General Alejandro Ordonez said that Piedad Cordoba, one of the most vocal opposition leaders who has negotiated the release of hostages seized by the FARC in the past, had given counsel to the leftist guerrillas.
"The senator ... exceeded the duties authorized by the government to negotiate humanitarian exchanges," Ordonez said.
The investigation into Cordoba was started due to files found on the computers of FARC spokesman, Raul Reyes, who was killed in 2008 in a military attack on Colombian rebels in neighboring Ecuador, Ordonez said.
Cordoba, according to her lawyer, will contest the ruling by the inspector general, whose office is in charge of monitoring the behavior of public officials.
In a major blow to the four-decade-old rebellion, Colombian troops killed top rebel military chief Mono Jojoy in a raid on his jungle camp last week. [ID:nN23139058]
The insurgents named Pastor Alape as Jojoy&${esc.hash}39;s replacement on Monday. Alape is a U.S.-wanted guerrilla commander, whom Washington accuses of heading the FARC&${esc.hash}39;s cocaine operations in the Middle Magdalena region in the central part of Colombia.
The FARC said in a statement that Alape would join the rebels&${esc.hash}39; seven-member central committee.
(Reporting by Luis Jaime Acosta; Editing by Paul Simao)
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