The White House has vowed to maintain cooperation with Colombia in its war against leftist rebels who have taken three Americans hostage, and denied that the captives were CIA agents.
"We will continue to work closely with Colombia and its government and its military and its police on how to combat the FARC," spokesman Mr Ari Fleischer said at President George W. Bush's Texas ranch.
Earlier, for the first time, the Revolutionary Armed Forces of Colombia (FARC) issued a statement claiming responsibility for the kidnapping and accused the three captives of working for the Central Intelligence Agency.
"They were DOD (Department of Defense) contractors, just as we've reported all along," said Mr Fleischer, who also disputed the rebels' claim to have shot down the aircraft.
The three hostages are believed to be the first US government employees kidnapped by Colombian rebels during the country's four-decade civil war.
The three went missing after their small plane went down in southern Colombia last week. Two others - one American and one Colombian - were found apparently shot dead near the wreckage. Columbian investigators said the plane had been hit by rockets and machinegun fire.
AFP