The International Committee of the Red Cross said Saturday it has made contact in Colombia with leftist guerrillas who said they wanted to release a captured US ex-soldier.

US ambassador Michael McKinley said the American, Kevin Scott Sutay, had nothing to do with the US military mission in Colombia and was in the country as a tourist.

"We demand that they free him as soon as possible," McKinley told reporters.

The Revolutionary Armed Forces of Colombia (FARC) said Friday it captured Sutay June 20 in the southern department of Guaviare.

It offered to release him as a gesture toward peace talks underway in Havana between the guerrilla group and the government.

"We are already in contact with the parties," a spokesman for the ICRC told AFP. "The ICRC is prepared to offer its good offices to facilitate this release."

The FARC said their captive served in the US Army from November 17, 2009, to March 22, 2013, including in Afghanistan in 2010-11.

McKinley, however, said he was a retired marine who was in the country on a tourist visit.

"He has nothing to do with the military mission, nothing to do with the armed conflict," he said.

Colombian Defense Minister Juan Carlos Pinzon also disputed that Sutay was anything other than an ordinary citizen.

"The information we have indicates that he is an American citizen who came to this part of the country and was even warned by police not to enter certain areas," he said.

The FARC "had promised not to kidnap, and they kidnapped an ordinary citizen," he added, calling the abduction absurd and an indication that the rebels' promises were "false."

Before entering into peace talks last year, the FARC pledged to end kidnappings for ransom of civilians and in April 2012 released the last 10 soldiers and police in captivity.

The rebel group, Colombia's largest with an estimated 8,000 fighters, has taken dozens of soldiers, police and politicians hostage over the course of its near 50-year-old insurgency.

Three US contractors -- Marc Gonsalves, Thomas Howes and Keith Stansell -- were held hostage from 2003 to 2008 after the aircraft they were flying crashed in rebel-held territory.

They were rescued in July 2008 in a Colombian army operation that also freed Ingrid Betancourt, a politician with dual Colombian-French citizenship.

Separately Saturday, Colombian President Juan Manuel Santos said his country was faced with a "real opportunity" for making peace with the FARC.

Talks between the rebels and the Colombian government opened in November in Cuba, in the fourth attempt since the 1980s to end the conflict that has left 600,000 dead, more than 3.7 million displaced and 15,000 missing.

"I say this not because I believe in the FARC, but because I believe in the seriousness of the process," he said in a speech that made no mention of Sutay's capture.

UN proposes to play role in FARC peace process
Bogota, Colombia / Colombia (AFP) July 20, 2013 - UN human rights chief Navi Pillay suggested Friday that the global body could contribute to Colombia's efforts to reach a peace deal with leftist FARC rebels, as she visited Bogota.

"The United Nations will certainly be ready to play a role, same as my office," she said in reference to talks started in Cuba last year aimed at ending the half-century-old conflict.

It "is very important to have independent monitors on the implementation of peace agreements, so I'm ready to play a role," she told a news conference at the end of her three-day visit.

Pillay's trip to the Latin American country was marked by controversy after President Juan Manuel Santos hypothesized about a possible closure of the local UN office, claiming to have made sufficient progress on human rights. He later backtracked.

"I do agree that it would be better if we are in the country," Pillay told reporters.

Officials in Bogota announced Thursday they had decided to extend by a year -- until October 31, 2014 -- the mandate of the UN's human rights office in the country.

Each year, the office -- whose mandate has been regularly renewed since it opened in 1997 -- publishes a report on the human rights situation in the country.

During her visit, Pillay met with the president, as well as with a dozen ministers and NGO representatives.

"I pay great tribute to what has been done. This government has taken enormous steps that will be very useful for full protection of human rights in this country," Pillay said.

She stressed, however, that more needed to be done to provide reparations to victims of the armed conflict.

"Right now I'm focusing on implementation," she said. "Why? Because I had listen to communities, I had (to) listen to NGOs, and they haven't found the benefits of these resources."

Formed in 1964, the Revolutionary Armed Forces of Colombia, or FARC by its Spanish acronym, is the country's largest guerrilla group, with an estimated 8,000 fighters.

The peace talks, which opened in November in the Cuban capital Havana, are the fourth attempt since the 1980s to bring peace to Colombia.

The war has ravaged Colombia for fifty years and has left 600,000 dead, more than 3.7 million displaced and 15,000 missing.