Colombian commandos have freed former presidential candidate Ingrid Betancourt, three Americans and 11 other hostages from leftist rebels, without firing a single shot.

Betancourt, a French-Colombian politician, had been held captive for more than six years by the Revolutionary Armed Forces of Colombia, also known as FARC.

"Thank you for your impeccable operation," Betancourt, clothed in military fatigues, told Colombia's top commanders. "The operation was perfect."

She appeared thin but healthy, although reports suggest she suffered from several health problems during her long ordeal.

The U.S. hostages were military contractors, and have been identified as Marc Gonsalves, Thomas Howes and Keith Stansell. They were captured in 2003, after their small plane crashed in the jungle.

The other 11 hostages were members of the Colombian security forces.

All of the hostages were freed Wednesday in the southern province of Guaviare. Colombian commandos tricked FARC members into releasing the captives, according to Defence Minister Juan Manuel Santos.

The group infiltrated the rebels and told a local commander in charge of the hostages they would take him to the top FARC leader, Alfonso Cano.

Instead, the commandos whisked the hostages away in helicopters and peacefully captured the rebels.

Betancourt said the commandos only revealed their true identity to the hostages once they were safely airborne.

"The chief of the operation said, `We're the national army. You're free,'" she said.

No one was killed or injured in the operation. Santos said it would go down in history "for its audacity and effectiveness."

FARC has tried to overthrow the Colombian government for more than 40 years, and still has dozens of hostages. The group's leader, Manuel Marulanda, died last March.

Six years

Betancourt's son, Lorenzo Delloye-Betancourt, said his mother's freedom was "the most beautiful news of my life."

FARC captured Betancourt in 2002 while she was running for Colombia's presidency. She had been a major critic of the leftist rebel group.

Before Wednesday, Betancourt had not been seen since 2003. According to the BBC and The Associated Press, she has suffered various ailments during her captivity, including Hepatitis B and tropical skin diseases.

A former hostage said rebels kept her chained to a tree after she attempted to escape.

Betancourt was born in Colombia but raised in Paris, and was once married to a French diplomat. French President Nicolas Sarkozy had made Betancourt's release a major priority for his government.

French Prime Minister Francois Fillon, visiting Canada for Quebec City's 400th anniversary, said it was "a huge joy to know that Ingrid Betancourt and other hostages are finally free."

He also praised Betancourt's family for "never giving up hope."

With files from The Associated Press