QUITO, July 29, 2010 (AFP) – Colombia and Venezuela faced off Thursday at a meeting of South American foreign ministers called to air accusations by Bogota that Colombian rebels were using Venezuelan territory to launch attacks.

Venezuelan Foreign Minister Nicolas Maduro said on arrival in Quito that his government had requested the meeting to respond to the "grave threats and grave attacks" on it by the government of President Alvaro Uribe of neighboring Colombia.

While accusing the Uribe government of "slander, manipulation, lies" against Venezuela and its President Hugo Chavez, Maduro said he would propose ways "we can retake the path of peace."

The meeting was the latest step in a diplomatic row stemming from Colombia's claim that some 1,500 guerrillas of the Revolutionary Armed Forces of Colombia (FARC) and National Liberation Army (ELN) -- both of which have been fighting Bogota for decades -- are now operating from Venezuela.

Colombia's Foreign Minister Jaime Bermudez said on his arrival that he would appeal to his South American colleagues for help in preventing Colombian rebel forces from taking refuge in Venezuela, or elsewhere.

"Colombia comes with a clear willingness to ask for an efficient cooperation mechanism so that neither the FARC nor the ELN, nor any criminal group can be present in Venezuelan territory, with the collusion of the authorities, or in any part of the world," Bermudez said.

However, he said he did not have high expectations for the meeting of the Union of South American Nations (Unasur), a group set up to foster regional cooperation on security issues.

Ecuador's Foreign Minister and Unasur host Ricardo Patino met with Maduro and Bermudez before calling the closed-door meeting to order at 4:00 pm (2100 GMT). He stressed the desire of all Unasur members for a peaceful solution to the dispute.

Chavez denounced the charges as a pretext for "armed aggression" and broke off diplomatic relations with Bogota.

The Colombian diplomat said that his country "has lots of evidence, lots of information" on the guerrilla presence.

Meanwhile, Brazilian President Luiz Inacio Lula da Silva announced he would travel to Venezuela and Colombia on August 6 for talks with their respective presidents as well as with Colombia's president-elect Juan Manuel Santos, who takes office August 7.

However, Uribe complained Thursday that Lula was approaching the crisis as if it were a case of personal conflicts.

The Brazilian leader is "ignoring the threat for Colombia and the continent that the presence of FARC terrorists in (Venezuela) represents," he said in a statement.

"The only solution that Colombia accepts is to not allow the presence of the terrorists... on Venezuelan territory," he said.

Separately, the head of US Southern Command urged Venezuela to investigate charges leftist guerrilla leaders operate from its territory.

"There is no reason to assume that it is not valid," General Douglas Fraser said in a talk Thursday at a Washington think-tank.

Fraser, who is responsible for all US military activities in Latin America, said the United States was looking at the evidence, saying it was "an allegation that needs to be treated seriously."