RIONEGRO, Colombia (Reuters) - U.S. Secretary of State Condoleezza Rice met Colombian President Alvaro Uribe on Friday in a high-profile show of support for a Washington ally locked in a dispute with Venezuelan leader Hugo Chavez.
Speaking in Caracas as Rice ended her two-day visit, Chavez blasted Colombia as a U.S. "imperialist" pawn seeking to foment a military confrontation and suggested relations with his Andean neighbour could only deteriorate.
Rice arrived in the Colombian city of Medellin on Thursday evening to rally support for a free trade agreement which U.S. Democratic lawmakers oppose but which the White House says could help counter Chavez's influence in Latin America.
Trade was the key issue but Washington has stood firmly behind Uribe as a dispute erupted over President Chavez's mediation with Marxist rebels in Colombia and his calls for them to be taken off U.S. and European Union terrorism lists.
"We know that Colombia faces many challenges but I want to assure that you will have a good friend in the United States as you go through those challenges," Rice said beside Uribe at an air force base near Medellin, without mentioning Chavez.
With the largest U.S. military and anti-drugs aid package outside the Middle East, Uribe has driven back the rebels who are still fighting Latin America's oldest insurgency. Violence has ebbed and foreign investment has soared.
Democratic leaders in the U.S. House of Representatives said last June that Colombia still needed to make much more progress to reduce violence against trade unionists and punish murderers before Congress would vote on the free trade pact.
Rice and other U.S. officials have presented the trade deal as essential to support an ally in a "tough" region.
Washington sees Chavez as a menace undermining democracy in Latin America by using his OPEC nation's oil wealth to build a socialist state and support leftist allies in Ecuador, Bolivia and Nicaragua.
Chavez says the White House is working to topple him.
"I accuse the government of Colombia of plotting a conspiracy, acting as a pawn of the North American empire, of plotting a military provocation against Venezuela," Chavez told a news conference.
"Unfortunately, everything suggests things will continue getting worse," he said.
He has already recalled his envoy from Bogota and threatened $6 billion in trade between the neighbours.
The clash with Chavez underscores the tough task Uribe faces in balancing his roles as a Bush administration partner and a neighbour to U.S. adversary Venezuela, where Colombia sends more than $4 billion in exports each year.
A delegation of U.S. lawmakers visiting Medellin with Rice were shown projects highlighting efforts to reduce violence, including meetings with former paramilitary fighters and victims displaced by the conflict now working on farms.
The delegation was impressed by progress made in Colombia, Rep. Eliot Engel, a New York Democrat, told reporters. But others were more cautious.
Rep. David Scott, a Georgia Democrat, said he was concerned about Colombia's long history of unsolved murders of trade unionists and the degree to which the Colombian government or military may be involved.
"You can't allow that to go unanswered," he said. "It's not a matter of the rightness or wrongness of the free trade agreement. It's right. The question is can you get the votes in the Congress when you have such a violent reputation."
In a letter to U.S. Trade Representative Susan Schwab released on Friday, Human Rights Watch said a vote should be delayed until the Colombian government makes more progress in rooting out the influence of demobilized paramilitary bosses and ensuring accountability for violence against unions.
The Uribe administration says it takes labour violence seriously and that the number of murders each year has fallen sharply. Uribe has also tripled spending on protection for unionists and human rights activists.
(Additional reporting by Brian Ellsworth in Caracas; Editing by Eric Walsh)