BOGOTA, June 8 (Reuters) - Colombian President Alvaro Uribe on Friday welcomed Group of Eight nations' support for his initiative to free hostages held by left-wing rebels, but a guerrilla leader he released from prison to try to negotiate a deal warned that any agreement remained elusive.

Uribe's move to free guerrilla commander Rodrigo Granda and around 150 others has fueled hopes of families a deal could be close with the Revolutionary Armed Forces of Colombia, or FARC, to swap jailed guerrillas for kidnap victims held for years in Latin America's oldest left-wing insurgency.

Granda was released on Monday after French President Nicolas Sarkozy asked Uribe to free him to help set up a deal over hostages including French-Colombian politician Ingrid Betancourt, kidnapped in 2002, and three Americans held in secret jungle camps by the FARC since 2003.

Uribe spoke in Washington where he was trying to persuade wary Democrats in the U.S. Congress to approve a free trade agreement and extend a multimillion-dollar military and counter-narcotics aid package.

"The G8 have understood the dimension of our humanitarian gesture," Uribe said.

In a statement at the end of their meeting in Germany, the world's industrialized nations recognized Uribe's measure as a positive step.

But in Bogota, Granda warned that a hostage deal was still far off because the FARC leadership had yet to approve his role as negotiator and he had not reached any accord with the Colombian or French governments.

"I am not going to create a miracle. I ask the relatives, the mothers of those held by the FARC, not to deceive themselves, and to have patience," Granda told reporters before flashing a victory sign and shouting "Long live the FARC."

Granda, who is known as the FARC's "foreign minister," said he did not know why Sarkozy had asked Uribe to free him. He is staying at the Roman Catholic Church episcopal conference in Bogota while the details of his possible role are decided.

He was captured in Venezuela in 2004 by undercover police agents who whisked him across the frontier to Colombia in an incident that sparked a diplomatic row between the nations.

The FARC insists that Uribe temporarily demilitarize an area the size of New York City to launch talks over the release of politicians, police and soldiers held for as long as nine years. Granda repeated the hostages could be freed if a safe haven was granted, but Uribe rejects that as unacceptable.

Betancourt, who has dual French and Colombian nationality, was captured while campaigning for the Colombian presidency. The three U.S. Defense Department contractors -- Marc Gonsalves, Keith Stansell and Thomas Howes -- were snatched after their aircraft crashed on an anti-drug mission.

(Additional reporting by Adriana Garcia in Washington)

AlertNet news is provided by