Venezuela opposition leader Juan Guaido called Tuesday for three days of protests against President Nicolas Maduro, hours after he was sworn in for another term as National Assembly speaker following a standoff with the armed forces.

Guaido was barred from entering the assembly by the National Guard for around half an hour in dramatic and chaotic scenes, while a rival claimant to the speaker's post occupied the chair.

"It's time to stand up and to stand up with force," Guaido said later during a press conference.

Venezuelan opposition leader and self-proclaimed acting president Juan Guaido shouts on his way to the National Assembly, in Caracas, on January 7, 2020, where he claimed the speaker's chair
Venezuelan opposition leader and self-proclaimed acting president Juan Guaido shouts on his way to the National Assembly, in Caracas, on January 7, 2020, where he claimed the speaker's chair AFP / Yuri CORTEZ

"We will mobilize for street protests on Thursday and Friday, and on Saturday we will all be in the streets."

Guaido, self-appointed acting president of Venezuela, leads the opposition to leftist Maduro, who remains in power despite Guaido's year-long effort to oust the man he calls a "usurper."

The National Assembly legislature is the only branch of government in opposition hands, and Guaido's holding of the speaker's post is important for continuation of his struggle with Maduro.

Venezuelan opposition leader and self-proclaimed acting president Juan Guaido speaks on a loudspeaker as helmeted security forces try to block his entry to the National Assembly
Venezuelan opposition leader and self-proclaimed acting president Juan Guaido speaks on a loudspeaker as helmeted security forces try to block his entry to the National Assembly AFP / Yuri CORTEZ

Guaido is backed by the United States and more than 50 other countries but, despite Venezuela's economic collapse, Maduro appears entrenched with crucial support from the armed forces. He is also backed by China, Russia and Cuba.

"Here we are, showing our face," Guaido said, taking his seat in the assembly after rival claimant Luis Parra and pro-government lawmakers left.

Venezuela's opposition lawmaker and self-proclamied parliament speaker Luis Parra attends a session at the National Assembly, in Caracas, on January 7, 2020 before the arrival of opposition leader Juan Guaido
Venezuela's opposition lawmaker and self-proclamied parliament speaker Luis Parra attends a session at the National Assembly, in Caracas, on January 7, 2020 before the arrival of opposition leader Juan Guaido AFP / Federico Parra

Lawmakers sang the national anthem but electricity to the chamber was cut off, leaving deputies to use flashlights on their mobile phones.

Guaido then raised his right hand and took the oath of office for another term as leader of the assembly.

Earlier, dozens of National Guard troops wearing helmets and carrying riot shields blocked Guaido from entering the building.

A caravan carrying Venezuelan opposition leader and self-proclaimed acting president Juan Guaido to the National Assembly, followed by journalists on motorcycles
A caravan carrying Venezuelan opposition leader and self-proclaimed acting president Juan Guaido to the National Assembly, followed by journalists on motorcycles AFP / YURI CORTEZ

"These are not barracks!" Guaido shouted.

Some of his allies and members of the press were also blocked from getting inside.

The opposition said on Twitter that four lawmakers were injured by "regime minions."

Parra, an opposition legislator accused of corruption, had declared himself speaker on Sunday after the armed forces had prevented Guaido from entering the building.

Venezuela's opposition leader Juan Guaido takes his place in the parliament speaker's seat
Venezuela's opposition leader Juan Guaido takes his place in the parliament speaker's seat AFPTV / Yorman MALDONADO

Guaido had declared Sunday that he was re-elected to his post after holding a legislative session alongside loyal deputies at the offices of a pro-opposition newspaper.

Crisis-hit Venezuela has been in political turmoil since last January when Guaido used his position as speaker to declare himself acting president in a direct challenge to the authority of Maduro.

The United States warned on Tuesday it could ramp up sanctions against Venezuela, and Secretary of State Mike Pompeo congratulated Guaido on his re-election.

"The Maduro regime's campaign of arrests, intimidation and bribery could not derail Venezuelan democracy, nor could its use of military forces to physically bar the National Assembly from accessing the parliament building," said Pompeo.

Speaking Tuesday on state broadcaster VTV, Maduro called Pompeo a "failed clown" for supporting Guaido, whose swearing in as speaker was "a show."

"The United States assumes it has the right to name the world's legislatures with (their) threats," he said.

And Maduro's Foreign Minister Jorge Arreaza tweeted that the US must "now assume that its strategy against Venezuela failed. They have not shown any skills as puppeteers and they lost their main puppet."

Parra was kicked out of his opposition party last month after an online news site accused him of corruption linked to the over-pricing of food imported for the Maduro government.

He remains a deputy and Maduro recognized Parra's election in a television address on Sunday. But even Maduro's left-wing allies Argentina and Uruguay have denounced the move.

Before Sunday's vote, Guaido said the Maduro government had bribed some opposition deputies to vote against him.

The opposition holds 112 of the 167 seats in the assembly.

As well as two claimants to the presidency and the position of assembly speaker, Venezuela has two legislatures.

Maduro then controversially set up a Constituent Assembly -- also made up exclusively of loyalists -- with power to legislate in its place.