Venezuela’s embattled president, Nicolás Maduro, has accused the White House of playing a direct role in an attempt to assassinate him and claimed “ultra-right locos” within Brazil’s incoming government were plotting to invade his country.

At a press conference in the presidential Miraflores palace in Caracas, Maduro said he had “no doubt” that the US government had ordered and authorized the botched strike against him last August with explosive-laden drones and continued to plot against him. He offered no evidence to support the allegations.

Maduro claimed the US hoped to install a rightwing dictatorship in Venezuela and accused the US media of waging an “incessant” media campaign against his government in order to justify a foreign military intervention in Venezuela.

The US national security adviser, John Bolton, had personally hatched a plan “to fill Venezuela with violence”, Maduro alleged, urging Donald Trump to abandon the supposed conspiracy and turn away from “conflict and confrontation”.

In November Bolton described Venezuela as part of a Latin American “troika of tyranny” that had “finally met its match”.

Last year Trump told reporters there were “many options” to resolve the Venezuelan crisis including a military one. In December the US defense secretary, James Mattis, called Maduro “an irresponsible despot” who would ultimately “have to go”.

Maduro vowed to resist what he called the “neo-fascist madness” of his foreign foes and called on the international community to denounce the alleged plot against him. “Our message to the world is: it’s time to defend Venezuela!” he said. “Venezuela will not be a victim of a neo-fascist aggression.”

“We will not retreat, we will not be brought to our knees, we will not give up. We will fight and we will guarantee Venezuela peace … whatever the price,” Maduro added.

“We don’t want violence, or international conflicts, or war, or coups. No, no, no, no. The people want progress, prosperity and coexistence.”

Venezuela’s president also lashed out at Brazil’s incoming president, Jair Bolsonaro, and his vice-president, Hamilton Mourão, who he claimed was obsessed with the idea of invading Venezuela.

“[This guy] has the face of a madman,” Maduro said of Mourão. “Saying a Brazilian military force is going to enter Venezuela is crazy talk.”

“Nobody in Brazil wants the incoming government of Jair Bolsonaro to get involved in a military adventure against the Venezuelan people,” he said.

Bolsonaro, who takes power on 1 January, has made no secret of his loathing of Maduro and last year vowed to “do whatever is possible to see that government be deposed”.

But in a recent interview with the Brazilian magazine Piauí, Mourão struck a more moderate tone: “It’s the Venezuelans who have to solve the Venezuelans’ problems,” he said.