By Lesley Wroughton
WASHINGTON (Reuters) - The United States named a special envoy to Colombian peace talks on Friday, responding to requests from both the Colombian government and leftists rebels for Washington to take a more active role in ending Latin America's longest-running war.
U.S. President Barack Obama named Bernard "Bernie" Aronson, a former U.S. assistant secretary of state for Inter-American Affairs from 1989 to 1993, to the role.
"President Obama has come to the conclusion that while significant obstacles remain, a negotiated peace in Colombia is absolutely worth pursuing and absolutely worth assisting if we are able to," Secretary of State John Kerry told reporters.
As a close ally of Colombia, the United States has "responsibility to do what it can in order to help Colombia to achieve that peace," Kerry said.
Colombian President Juan Manuel Santos requested a more direct American role during a visit by Kerry to Bogota in December.
Santos staked his presidency on peace talks, winning re-election last year against a right-wing opponent who had threatened to bring them to a halt.
"We are grateful to President Obama and his government for this new gesture," Santos said in a statement.
The conflict between the Colombian government and Marxist-inspired rebels from the Revolutionary Armed Forces of Colombia (FARC) has killed more than 220,000 people since 1964.
The FARC has been calling for U.S. involvement since the peace talks began in Cuba two years ago and welcomed the announcement in a statement on Friday, thanking the Americans.
"We consider it a necessity, considering the permanent presence and impact that the United States has in Colombia's political, economic and social life," the FARC said.
It was unclear whether the recent change in U.S. relations with Cuba played a role. Washington and Havana have begun a historic effort to restore diplomatic relations after more than 50 years of hostility.
Aronson, a veteran diplomat who was also involved in peace efforts in Nicaragua and El Salvador, said the United States "will not take a place at the negotiating table, but we can push, prod, cajole, and clarify and help wherever we can."
Colombian negotiators have reached partial accords on political participation for ex-rebels, land reform and an end to the illegal drug trade. They are currently negotiating victim reparations and demobilization.
Once all five partial accords are reached, the two sides will review the entire agreement, which would then be placed before Colombian voters for ratification.
(Additional reporting by Julia Symmes Cobb in Bogota and Nelson Acosta in Havana; Editing by Susan Heavey and James Dalgleish)