Thousands of protesters have taken to the streets of Venezuela's capital Caracas in support of President Nicolás Maduro - and his self-proclaimed interim successor Juan Guaidó.
Guaidó said the country's opposition movement would "carry on in the streets". Maduro told supporters he was the only president of Venezuela.
Guaidó declared himself president last month and is backed by the US and several Latin American countries.
Russia and China back President Maduro.
The stand-off began days after Maduro was sworn in for a second term, following disputed elections which many opposition leaders did not contest because they were in jail or boycotting them.
Guaidó, who is head of Venezuela's National Assembly, says the Constitution allows him to assume power temporarily when the President is deemed illegitimate.
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Addressing thousands of supporters in the capital Caracas, Guaidó said protests would continue until his supporters achieved "freedom".
But a pro-Maduro crowd gathered to mark the 20th anniversary of the rise to power of his predecessor, the socialist leader Hugo Chávez. Maduro accused international media of ignoring demonstrations by pro-government supporters.
The rival protests come a day ahead of a deadline given to Maduro by major European countries to announce new presidential elections - otherwise, they would also recognise Guaidó.
Military support is seen as crucial to Maduro's hold on power. Many supporters at Saturday's rally were seen wearing the khaki uniforms of the government militia.
Ahead of the protests, a high-ranking Air Force general announced his support for Guaidó
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Gen Francisco Yanez, the force's head of strategic planning, called on other members of the military to join him in defecting. It is not clear when or where the message was recorded.
In response,
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But US National Security Adviser John Bolton called on the rest of the country's military to join forces with Gen Francisco Yanez.
@AmbJohnBolton said, "Another Venezuelan military officer recognizes the legitimate President of VZ. The US calls on all military members to follow General Yánez’s lead, and to protect the peaceful protestors supporting democracy."
Guaidó, meanwhile, says he has held secret meetings with the military to win support for ousting Maduro.
He has also reached out to China in the hope of improving relations with the country.
In comments published in the South China Morning Post on Saturday, Guaidó said he wanted a "productive and mutually beneficial" relationship with China, adding that he was ready to engage in dialogue "as soon as possible".