US President Donald Trump and Venezuela's self-proclaimed interim president Juan Guaido have agreed to maintain regular contact amid planned protests in coming days, according to a White House spokeswoman.
Mr Trump spoke with Mr Guiado by phone "to reinforce President Trump’s strong support for Venezuela's fight to regain its democracy," White House spokeswoman Sarah Sanders said in a statement.
The United States has recognised Mr Guaido, an opposition leader and head of Venezuela's national assembly, as the president of the country.
In an interview with CNN that aired yesterday, Mr Guaido said he had spoken with Mr Trump a number of times.
When asked about a possible military option in Venezuela, Mr Guaido said all options were on the table, CNN said.
Meanwhile in an interview with Moscow's RIA news agency, Venezuela's socialist leader Nicolas Maduro accused Mr Trump of ordering his assassination while his main global backer Russia called for mediation in a standoff deepening geopolitical splits.
The fight to control Venezuela, which has the world's largest oil reserves, has intensified with new US sanctions and legal moves that may bring Mr Guaido's arrest.
Meanwhile, Venezuela's highest court has barred Mr Guaido from leaving the country.
It has also frozen the bank accounts of the 35-year-old head of the National Assembly for the duration of a "preliminary investigation" for having "caused harm to peace in the republic," court president Maikel Moreno said.
The Supreme Tribunal of Justice is known to be loyal to President Maduro.
Mr Guaido says that, as head of the National Assembly, he has a constitutional right to assume power temporarily when the president is deemed illegitimate.
The move came after the US State Department revealed that Mr Guaido has been handed control of Venezuela's US bank accounts.
US Secretary of State Mike Pompeo signed off on the order last week, which was then followed on Monday by US sanctions targeting Venezuela's state oil giant PDVSA, the cash-strapped government's main source of hard currency.
"This certification will help Venezuela's legitimate government safeguard those assets for the benefit of the Venezuelan people," State Department spokesman Robert Palladino said in a statement.
Mr Guaido shrugged off Mr Maduro's efforts to choke his progress as "nothing new".
"I'm not dismissing the threats, the persecution at this time, but we're here, we're continuing to do our jobs," he told reporters as he arrived at the National Assembly.
Mr Guaido sent a message to the country's top court on Twitter warning that "the regime is in its final stage".
"You shouldn't sacrifice yourselves for the usurper and his gang," he added.
Meanwhile, Mr Maduro has said he was ready for talks with the opposition with the participation of international mediators.
Speaking to RIA, he said that the question of international mediators could be decided within hours.
Mr Maduro also said that he was sure his side would "emerge the victors".
In Washington, Mr Trump's national security advisor warned of "serious consequences" if any harm comes to the Venezuelan opposition leader.
"Let me reiterate - there will be serious consequences for those who attempt to subvert democracy and harm Guaido," John Bolton tweeted.