Venezuela's acting president Nicolas Maduro has accused former US officials Roger Noriega and Otto Reich of plotting to kill him to prevent his victory in next week's presidential elections.
Speaking at a televised campaign event on Saturday, Maduro said the plot also involved "right-wing forces" from El Salvador, which had already dispatched paid assassins to Venezuela to implement the plan.
"Their goal is to kill me," said Maduro, who had been designated by the late Venezuelan leader Hugo Chavez as his heir apparent. "They want to kill me because they know they cannot win free and fair elections."
A presidential election to replace Chavez, who died of cancer last month, will be held on April 14.
Maduro said part of the plot also involved sabotaging the nation's electrical grid.
Parts of oil-rich Venezuela suffer from regular power outages, a problem opposition leader Henrique Capriles had seized upon to criticize the socialist government that Chavez led for 14 years until his death on March 5.
On Thursday, Maduro also accused the opposition of plotting to sabotage the national power grid to cause a blackout ahead of the election.
He repeated the claim on Saturday, adding that he was aware that one of the leaders of Capriles' Justice First party had met with an employee of the US Embassy in Caracas to discuss plans for "a general blackout" in the state of Bolivar, where most of Venezuela's electrical power is generated.
"They are clearly hatching a conspiracy," Maduro insisted, adding that the Venezuelan government will consider "an appropriate diplomatic measure." He did not elaborate.
A conservative Mexican-American, Roger Noriega served as US permanent representative to the Organization of American States (OAS) from 2001 to 2003.
Otto Reich, a Cuban-American, was the US president's special envoy for the Western Hemisphere, assistant secretary of state and US ambassador to Venezuela.
While vocal critics of Venezuelan policies, both have repeatedly denied any involvement in Venezuelan affairs.
Venezuela and the United States have not exchanged ambassadors since 2010, and are represented in each other's capitals only by charge d'affairs. Tensions between the two countries have been rising since the day of Chavez's death, when Maduro announced the expulsion of two US military attaches.
Washington reciprocated by expelling two Venezuelan diplomats who were decorated on Wednesday by Foreign Minister Elias Jaua.
Last month, Venezuela said, without offering specifics, that it had suspended a "channel of communications" with Washington as it ratcheted up tension ahead of the elections.
Jaua said the move was a response to "interventionist statements" by US Assistant Secretary of State for Western Hemisphere Affairs Roberta Jacobson, who called for "open, fair and transparent" elections on April 14.