The United States is holding direct communications with members of Venezuela's military urging them to abandon leader Nicolas Maduro, a senior White House official said.

Key points: Winning over the support of the military is critical in toppling Nicolas Maduro's regime

Winning over the support of the military is critical in toppling Nicolas Maduro's regime The US has not ruled out imposing further sanctions on Maduro "to accept a legitimate democratic transition."

The US has not ruled out imposing further sanctions on Maduro "to accept a legitimate democratic transition." Self-declared president Juan Guaido says the 2018 elections were a sham and has promised free and fair elections

The Trump administration expects further military defections from Mr Maduro's side, the official told Reuters in an interview, despite only a few senior officers having done so since opposition leader Juan Guaido proclaimed himself interim president last month.

"We believe these to be those first couple pebbles before we start really seeing bigger rocks rolling down the hill," the official said this week, speaking on condition of anonymity.

"We're still having conversations with members of the former Maduro regime, with military members, although those conversations are very, very limited."

Nicolas Maduro has told Venezuelans "not to trust the gringos". ( AP/Reuters )

The official declined to provide details on the discussions or the level at which they are being held, and it was unclear whether such contacts could create cracks in the Venezuelan socialist leader's support from the military, which is pivotal to his grip on power.

With the Venezuelan military still apparently loyal to Mr Maduro, a source in Washington close to the opposition expressed doubts whether the Trump administration has laid enough groundwork to spur a wider mutiny in the ranks where many officers are suspected of benefiting from corruption and drug trafficking.

Mr Guaido says the May 2018 vote in which Mr Maduro won a second term as president was a sham and on January 23, invoked a constitutional provision to declare himself president, promising free and fair elections.

Few senior military figures have got behind self-declared president Juan Guaido. ( Reuters: Carlos Garcia Rawlins )

The US Government also sees European allies as likely to do more to prevent Mr Maduro from transferring or hiding Venezuela government assets held outside the country, the US official said.

Major European countries have joined the United States in backing Mr Guaido but they have stopped short of the sweeping oil sanctions and financial measures that Washington has imposed.

At the same time, the Trump administration is readying further possible sanctions on Venezuela, the official said.

Previous rounds have targeted dozens of Venezuelan military and government officials, including Mr Maduro himself, and last month finally hit the OPEC member's vital oil sector.

But the administration has stopped short of imposing so-called "secondary" sanctions, which would punish non-US companies for doing business with the Venezuela government or the state oil monopoly PDVSA.

The US official said that Washington had every tool available to apply pressure on Mr Maduro and his associates "to accept a legitimate democratic transition".

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Reuters