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By Hugh Bronstein

BOGOTA, July 2 (Reuters) - Colombian politician Ingrid Betancourt was as shocked as her rebel captors when the aid workers supposedly transporting her to a new location turned out to be government soldiers on a rescue mission.

The operation on Wednesday to free the former presidential candidate, three Americans and 11 other hostages relied on trickery against the 4-decade-old FARC guerrilla group.

Soldiers posed as members of a fictitious nongovernmental organization sympathetic to the rebels and pretended to fly the hostages by helicopter to meet with rebel leader Alfonso Cano.

"We were forced to get on the helicopter handcuffed, which was very humiliating," a pale but smiling Betancourt said at the Bogota air force base where she was reunited with her mother after six years in captivity.

"Then, all of a sudden, they disarmed the two guerrillas who were on the helicopter with us and the chief of the operation shouted, 'We are the Colombian army and you are free!'" she said. "The helicopter almost crashed because we all started clapping and screaming and jumping up and down."

A tearful Betancourt, who the left-wing guerrillas often forced to sleep chained by the neck, thanked Colombia's army for what she called its audacious and "impeccably executed" rescue.

She also thanked a captive army nurse who helped her survive her ordeal, marked by malnutrition, insect bites and jungle diseases. The nurse, William Perez, was rescued in the same operation as Betancourt.

Her hair braided and wearing a camouflage vest, Betancourt recalled seeing the FARC commander who had held her and others hostage for the last four years suddenly stripped of his guns.

"I saw this guerrilla commander, who had so often been cruel to us, on the floor," she said. "But I did not feel happiness. I felt sad."

The entire operation took 22 minutes and 13 seconds, said Gen. Freddy Padilla, head of Colombia's armed forces. The two rebels disarmed aboard the helicopter were in custody.

HIGH PROFILE CAPTIVE

Betancourt was snatched during her 2002 campaign for the presidency, in which she ran on an anti-corruption platform.

The rescue, carried out without a shot fired in the southern jungle province of Guaviare, is a huge victory for popular President Alvaro Uribe, an anti-guerrilla hard-liner who has used billions of dollars in U.S. aid to push the rebels onto the defensive, cut crime and spur economic growth.

Betancourt, 46, was the highest profile captive held by the Revolutionary Armed Forces of Colombia, or FARC, Latin America's oldest surviving left-wing insurgency.

"I feel like I'm back from a trip into the past, into prehistoric times," Betancourt said.

"It has been a long time since I've seen an electric light or had running water or hot water."

She was last seen in a rebel video at the end of last year looking ill, gaunt and despondent.

The freed Americans -- Marc Gonsalves, Keith Stansell and Thomas Howes -- all worked for Northrop Grumman and were captured in 2003 after their light aircraft crashed in the jungles while on a counternarcotics operation.

They arrived in the United States late on Wednesday night. (Reporting by Hugh Bronstein, Javier Mozzo and Alisha Laventure; Editing by Doina Chiacu)

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