* Brazil, Chile join dispute over U.S. troops in Colombia
* Colombia seen growing isolated in Andean region
* Diplomatic tensions seen increasing in months ahead
By Hugh Bronstein
BOGOTA, Aug 3 (Reuters) - A plan to increase U.S. troops in Colombia is drawing opposition not just from left-wing populist leaders in the region but from the moderate governments of Brazil and Chile as well.
The spreading criticism threatens to isolate Colombia from its neighbors as it combats a cocaine-funded insurgency.
The government is expected to sign an expanded U.S. military pact this month after a final round of talks. Colombia, Washington’s main ally in the region, says the plan is aimed at strengthening anti-drug efforts.
But leftist Venezuelan leader Hugo Chavez accuses the United States of setting up a military platform in Colombia from which to "attack" its neighbors.
Chavez allies in Ecuador, Bolivia and Nicaragua were quick to blast the plan as well. But Colombia was shocked late last week when Chile, a model of free-market policies, and regional heavyweight Brazil voiced concern about the deal as well.
"I don’t like the idea of an American base in the region," Brazilian President Luiz Inacio Lula da Silva said.
Chile’s President Michelle Bachelet called the plan "disquieting" and said it should be discussed at the Aug. 10 meeting of the South American Unasur group of nations.
But Colombia says President Alvaro Uribe and his foreign minister will not attend the summit.
The meeting will be held in Ecuador, which has broken off diplomatic relations with Colombia over a 2008 anti-rebel bombing raid carried out on Ecuador’s side of the border.
Ecuador and other socialist governments in the region are deepening economic ties with Russia, China and Iran, while denouncing Uribe for his ties to U.S. "imperialists".
"Colombia is increasingly isolated from its neighbors," said Bogota-based security analyst Armando Borrero.
"This has a snow-ball effect in that it makes the government even more reliant on Washington," he added.
Chavez last week called Venezuela’s ambassador back from Bogota over a scandal in which Venezuelan officials are accused of providing Swedish-made anti-tank rockets to the Revolutionary Armed Forces of Colombia, or FARC, rebel group.
Colombian and Swedish authorities asked Venezuela for an explanation after the rockets were found in a FARC arsenal.
Chavez denies helping the guerrillas and his response to the rockets scandal has been to threaten to nationalize Colombian businesses in Venezuela and to blast the upcoming U.S.-Colombia military pact.
Ecuador has shut down U.S. drug interdiction flights that had been run out of a base on the country’s Pacific coast.
Washington is negotiating a plan to relocate those operations in Colombia, which has received billions of dollars in U.S. aid aimed at fighting the drug trade and the rebels, whose 45-year-old insurgency kills and displaces thousands of people every year.
Colombia is frustrated by the reaction to the talks.
"Where was the hysteria when these operations were being run out of Ecuador," said a high-level official in Colombia’s defense ministry who asked that his name not be used.
"Mexico is having the worst security crisis in its history due to the drug trade and people are saying we should not help them by doing interdiction operations in the Pacific. It’s ridiculous," the official said.
Police report an increase in makeshift submarines hauling tons of cocaine from Colombia’s Pacific coast to Mexico, where violence has increased among gangs fighting over routes used to smuggle the drug into the United States.
Under the existing pact, the United states can have up to 800 uniformed military personnel in Colombia at one time. Those soldiers help plan counter-insurgency missions but they are not allowed in combat, a rule that will not change under the new military accord.
There are currently less than 300 uniformed Americans in Colombia and the expanded deal will not push that number above the limit of 800, according to the U.S. embassy in Bogota. (Additional reporting by Raymond Colitt in Caracas, editing by Philip Barbara)