Venezuelan President Nicolas Maduro lashed out Wednesday at what he said was a plot to assassinate him directed by the White House and involving the right-wing governments of Colombia and Brazil. Venezuela's leader repeated his frequent warning that a U.S. invasion is imminent — this time giving details.

He accused U.S. National Security Adviser John Bolton of overseeing a plot to replace him with a dictator. He alleged that Washington is using "dirty dollars, bled from the U.S. empire" to train 734 mercenaries in neighboring Colombia to carry out the plot. "I come again to denounce the plot which is being prepared from the White House to violate Venezuelan democracy, to assassinate me and to impose a dictatorial government in Venezuela," he said. Troops were being trained in the United States and Colombia to carry out the plot, he alleged.

The Venezuelan leader told foreign correspondents in Caracas that his government had "good information" that Bolton had been "assigning missions for military provocations on the border."

U.S. President Donald Trump and his Colombian counterpart Ivan Duque have been sharply critical of Maduro's leftist regime, and Trump in October hinted at a potential military response to resolve Venezuela's crippling economic crisis.

The Venezuelan leader had already castigated Washington in a speech on Sunday, saying it planned to carry out a coup with support from Colombia, although on that occasion he did not mention Brazil.

Maduro raised Washington's ire this week by announcing military exercises on Venezuelan soil with the participation of Russia, which sent two nuclear-capable long-range bombers to Caracas. The Venezuelan leader begins a second six-year term on Jan. 10, having won elections in May that were boycotted by the opposition.

While taking a forceful tone, Maduro left open the option for dialogue with rival nations for a peaceful solution, calling on anybody in Trump's administration to sit down for talks. "Venezuela does not kneel down, does not surrender. Venezuela will continue in peace and democracy," Maduro said. "Let the American empire know!"