* Brazil, Argentina call for regional summit with U.S.
* Venezuela, Ecuador warn of grave threat of bases
* Colombia says will oversee U.S. troops in the country
(Updates with South American call for summit with U.S. over Colombia bases plan)
By Eduardo Garcia and Walker Simon
QUITO, Aug 10 (Reuters) - Brazilian President Luiz Inacio Lula da Silva on Monday urged regional leaders to seek a summit with the United States to defuse tensions over a Colombian plan to allow U.S. troops more access to its military bases.
The U.S. proposal to use seven Colombian bases has fueled a fight between U.S. ally Colombia and Andean leftist leaders in Venezuela, Ecuador and Bolivia and also stirred concern from Chile and regional heavyweight Brazil.
Monday’s summit of the Unasur regional group in Quito was was called to hand over the group’s presidency to Ecuador and discuss issues such as financial systems and counter-narcotics but the U.S.-Colombia base plan dominated. Venezuelan President Hugo Chavez, a fierce U.S. foe, and his allies blasted the proposal as an aggression.
Washington has given Colombia, the world’s No. 1 cocaine producer, more than $5 billion in aid to fight drug traffickers and rebels. It now wants to relocate a hub for anti-drug operations from Ecuador to Colombia.
Colombian President Alvaro Uribe, who did not attend Monday’s summit, says the plan is an extension of existing accords.
Colombia’s defense minister will attend an Aug. 24 meeting with his South American counterparts to discuss the bases, a Colombian Foreign Ministry official told the summit.
In proposing a summit with the United States to discuss the base plan, Lula said, ”People will hear things that they don’t like but we have to talk clearly. This will be resolved with conversation, with people showing up.
“At a given movement, Unasur can call for a meeting with the United States to discuss topics of interest to the region.”
Uribe has toured South America to ease concern about the U.S. plan and more moderate governments said it was a sovereign matter. But leftists led by Chavez were furious and the socialist leader has taken economic measures against Colombia.
“I have the moral obligation to warn about the danger,” Chavez said. “This could be the start of a new tragedy ... The winds of war are beginning to blow.”
Ecuador’s President Rafael Correa, who began a second term on Monday, called the base plan “an open provocation.”
Tensions have simmered in the Andes since last year when Colombian troops raided across the border to kill a Colombian FARC rebel commander in his camp in Ecuador. Venezuela and Ecuador briefly moved troops to their borders before the crisis was defused at a summit in the Dominican Republic.
U.S. President Barack Obama on Friday denied the United States is planning to set up military bases in Colombia as part of the upgraded security agreement and said he has no intention of sending large numbers of additional troops.
The plan is expected to increase the number of U.S. troops in Colombia above the current total of less than 300 but not above 800, the maximum permitted under the existing military pact, officials have said.
“It is essential to call a meeting of the presidents of Unasur,” said Argentine President Cristina Fernandez, offering to host a new summit. “A state of belligerency is being created in the region.”
Editing by Patrick Markey and Bill Trott