Venezuela said it derailed a plot to kill President Nicolas Maduro, arresting two hitmen it said wanted to assassinate the leftist leader on orders from a Colombian right-wing former president.
Interior Minister Miguel Rodriguez said two Colombians were arrested on August 13.
The pair, Victor Johan Guache Mosquera and Erick Leonardo Huertas Rios, were part of "a group of 10 men who were coming to carry out the murder of the president", working with former Colombian president Alvaro Uribe, Rodriguez alleged.
They were part of a support team for a "highly experienced hitman" identified by the alias David, whom they reported to directly and who was to personally carry out the assassination, the minister said.
David, Rodriguez charged, was taking orders from a Colombian who is in prison, Oscar Alcantara Gonzalez, alias "Gancho Mosco", who allegedly works for Uribe.
"We have no doubt that Alvaro Uribe Velez has knowledge of all these things ... and we are not the least bit surprised that he is the one giving orders through operatives," Rodriguez said.
The Colombian ex-president, who held office from 2002-2010, denied the plot, branding the allegations as slurs.
In an interview with Colombian television, Uribe said he would rather talk about "important issues and not the slurs of the dictatorship".
Venezuelan opposition leader Henrique Capriles, who lost the April presidential vote to Maduro and is contesting the results, shrugged off the alleged plot, saying: "Nobody believes that tall tale."
In June, Rodriguez alleged that Maduro was targeted by a separate assassination plot launched from Colombia and the United States. Venezuela made frequent allegations of assassination plots against late leftist president Hugo Chavez and has continued to do so under Maduro, his hand-picked successor.
Official results gave Maduro, 50, a razor-thin margin of just 1.5 per cent over Capriles, 41, in the April 14 election.