The United States has dismissed an accusation from Venezuela’s president that vice-president Joe Biden conspired to overthrow him as “patently false”, arguing that President Nicolas Maduro was merely trying to distract the world’s attention from his government’s abuses of basic rights.

The exchange of barbs undermined hopes that the US and Venezuela could pursue improved ties following a rapid deterioration of relations last year. Just one month ago, Maduro and Biden shook hands in Brazil in an impromptu meeting in which both leaders expressed an interest in warmer relations.

In a televised address over the weekend, Maduro claimed that Biden sought to foment the overthrow of his socialist government during a Caribbean energy summit Biden hosted last month in Washington. According to Maduro, Biden told Caribbean heads of state that the Venezuelan government’s days were numbered and it was time they abandon their support.

“What vice-president Jose Biden did has no name,” Maduro said. “Vice-president Biden: Look me in the eyes. I saw you in Brazil, I gave you my hand. You, who said this is a new era for relations in Latin America, were going to conspire against Venezuela.”

Maduro, who is struggling to keep Venezuela’s oil-dependent economy afloat despite mounting problems, frequently accuses foreign governments of conspiracies, coup attempts and assassination plots, including the US.

“President Maduro’s accusations are patently false and are clearly part of an effort to distract from the concerning situation in Venezuela, which includes repeated violations of freedom of speech, assembly, and due process,” Biden’s office said in a statement.

Such rhetoric was a sharp departure from the month before, when Biden and Maduro chatted on New Year’s Day on the sidelines of Brazilian President Dilma Rousseff’s swearing-in ceremony. A photograph of Biden and Maduro smiling warmly at each other became a meme in Venezuela, and Maduro described the meeting as “cordial.” US officials said after that meeting that Biden discussed ways Venezuela could pursue better relations with the US, including by releasing political prisoners.

Venezuela’s economy has suffered as the price of oil plummets, with widespread shortages and galloping inflation fueling frustration with Maduro’s leadership. The US and Venezuela have not exchanged ambassadors since 2010.