(Updates with helicopters landing in Colombia; adds details)

By Nelson Bocanegra

VILLAVICENCIO, Colombia, Dec 28 (Reuters) - Venezuelan President Hugo Chavez sent helicopters into Colombia on Friday to pick up three hostages, including a boy born in captivity and held for years by Marxist rebels in jungle camps.

The two helicopters arrived in the flat, hot and humid town of Villavicencio at the foot of Colombia's Andes mountains on Friday afternoon and will fly off to collect the hostages when the rebel captors give them the go-ahead.

Speaking at a Venezuelan military base as the helicopters took off for Colombia, the socialist Chavez said the main rescue operation had been delayed until the weekend because the rebels had not yet told him where the hostages are being held.

"We have a little problem," said Chavez, a former paratrooper, as he crouched over a map, dressed in military fatigues and a red beret. "There is bad weather, they are traveling and they have difficulty communicating in the jungle."

He had earlier said Consuelo Gonzalez, Clara Rojas and her son Emmanuel could be free within hours. Emmanuel, whose father is a guerrilla fighter, was born in a rebel camp and is thought to be four years old.

Although wary of Chavez and his fierce anti-U.S. rhetoric, Colombia's conservative government this week agreed to let him fly Venezuelan aircraft painted with the colors of the Red Cross deep into its territory to collect the hostages.

Chavez was told last month by Colombian President Alvaro Uribe to stay out of hostage negotiations with guerrilla leaders but he apparently continued with secret talks and negotiated the freedom of the three captives.

LONG WAR

The Revolutionary Armed Forces of Colombia, or FARC, controls large jungle areas and holds hundreds of hostages, including politicians, soldiers and police, as part of a long war against the state.

As the mission began, Chavez toured the air force base close to the Colombian border with foreign envoys, including former Argentine President Nestor Kirchner, who will join the main rescue party over the weekend.

U.S. film-maker Oliver Stone, who is making a documentary about Latin America, was also with Chavez at the base and will travel to Colombia on Saturday to observe the mission. He said he was a fan of Chavez and called him a "great man."

Even when the Colombian rebels tell Venezuelan and Red Cross officials where to pick up the hostages, rough terrain and poor weather conditions could cause further delays.

The release could help pave the way for the freeing of other rebel-held captives, including French-Colombian politician and former Colombian presidential candidate Ingrid Betancourt, in exchange for jailed guerrillas.

It would also give Chavez a political victory just weeks after he lost a referendum vote that would have allowed him to run for reelection indefinitely and given him sweeping powers to accelerate his socialist revolution in Venezuela.

Chavez will not take part in the rescue party, but will receive the freed hostages at the military base, where relatives are also expected to gather.

"I want them in my arms. As the moment draws closer, I think I am dreaming and I need someone to pinch me," Rojas' mother, Clara de Rojas, said after flying from Colombia to the Venezuelan capital on Thursday night.

Rojas was Betancourt's vice-presidential running mate when they were both captured by the FARC in 2002, and Gonzalez, a former lawmaker, was snatched the year before. (Additional reporting by Frank Jack Daniel in Caracas and Hugh Bronstein in Bogota; Editing by Kieran Murray)

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