US President Donald Trump has said he recognises Venezuelan opposition leader Juan Guaidó as interim president.
Tens of thousands of Venezuelans are taking to the streets in protest against President Nicolás Maduro.
Mr Guaidó, who called for the demonstrations, declared himself acting leader in Caracas on Wednesday.
Mr Maduro was sworn in for a second term earlier this month, amid widespread allegations of vote-rigging.
Venezuela has been in economic freefall for a number of years under his leadership.
Hyperinflation and key shortages, including of food, has forced millions out of the country.
Early images from Wednesday’s protests showed some demonstrators facing off against National Guard security forces in the capital.
Mr Guaidó, who is head of the country’s National Assembly, has called on armed forces to disobey the government.
Activist groups said earlier that at least four people were killed overnight ahead of the demonstrations.
There are reports of tens of thousands of people out on streets across the country – including some counter-demonstrations being held in support of Mr Maduro.
What did Mr Trump say?
In a statement on Wednesday, described Mr Maduro’s leadership as “illegitimate” and said the country’s congress, led by Mr Guaidó, was the only “legitimate branch of government” in the country.
“The people of Venezuela have courageously spoken out against Maduro and his regime and demanded freedom and the rule of law,” his statement said.
In his announcement, he also urged others to follow his lead.
The Organization of American States (OAS) has also recognised Mr Guaidó as leader.
“Our congratulations to @jguaido as acting President of #Venezuela. You have all our recognition to launch the return of democracy to the country,” Secretary General Luis Almagro said in a tweet.