Hugo Chavez and Alvaro Uribe left presidential decorum at the door on Monday, when the two got into a shouting match during a diplomatic meeting.
The South American presidents were attending, somewhat ironically, the "Unity Summit" near Cancun, Mexico, when tempers flared.
According to an unnamed diplomat, the two argued first about trade. Venezuelan President Chavez then claimed that Colombia's president was planning to assassinate him and threatened to walk out of the conference.
Uribe's response was forthright. "Be a man!" he reportedly shouted. "These issues are meant to be discussed in these forums. You're brave speaking at a distance, but a coward when it comes to talking face to face."
Chavez then reportedly told Uribe to "go to hell."
Cuban President Raul Castro had to intervene to calm down the verbal sparring, according to sources. "How is it possible that we're fighting at a summit intended to unite Latin American and Caribbean countries?" he said.
The incident is likely to further the political tension between the two countries, where Colombia's cooperation with US military has angered its neighbors. Chavez has long been an outspoken critic of US foreign policy.