The Australian Government has recognised Venezuela's Opposition Leader Juan Guaido as the country's legitimate leader.

In a statement, Foreign Affairs Minister Marise Payne said Australia would support Mr Guaido until elections were called.

It comes after US President Donald Trump moved to do the same, leading Venezuelan President Nicolas Maduro to ask US diplomats to leave the country although he later released a statement saying he had suspended the expulsion to provide a 30-day window for negotiation.

So who is Juan Guaido, why does Australia and Mr Trump believe he's Venezuela's legitimate leader, and does anyone else agree?

Here's what you need to know.

Who is Juan Guaido?

At the rally, Juan Guaido called for free elections to end Mr Maduro's rule. ( Reuters: Carlos Garcia Rawlins )

Juan Guaido — whose surname is pronounced GWAYD-oh — is the leader of Venezuela's Opposition-led National Assembly.

He declared himself interim president at an anti-Government rally last night, before thousands of chanting demonstrators who want Mr Maduro to resign.

Mr Maduro started his second term as Venezuela's President on January 10 following a widely boycotted election last year, which many foreign governments have described as a sham.

"I swear to assume all the powers of the presidency to secure an end to the usurpation," Mr Guaido said.

Venezuela's constitution says if the presidency is determined to be vacant, new elections should be called in 30 days and the head of congress should assume the presidency in the meantime.

But Mr Maduro has so far refused to step down and has accused the Opposition of seeking to stage a coup.

Why has Australia and Donald Trump sided with Guaido?

In a statement, Ms Payne said Australia was urging all parties to respect the rule of law.

Here's what she said:

"Australia calls for a transition to democracy in Venezuela as soon as possible," Senator Payne said.

"We now urge all parties to work constructively towards a peaceful resolution of the situation, including a return to democracy, respect for the rule of law and upholding of human rights of the Venezuelan people."

Mr Trump also sided with Mr Guaido because the US administration sees Mr Maduro's Government as an "illegitimate regime".

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Here's what he said in his official statement:

"Today, I am officially recognising the president of the Venezuelan National Assembly, Juan Guaido, as the interim President of Venezuela.

"In its role as the only legitimate branch of government duly elected by the Venezuelan people, the National Assembly invoked the country's constitution to declare Nicolas Maduro illegitimate, and the office of the president therefore vacant.

"The people of Venezuela have courageously spoken out against Maduro and his regime and demanded freedom and the rule of law.

"I will continue to use the full weight of the United States economic and diplomatic power to press for the restoration of Venezuelan democracy.

"We encourage other Western Hemisphere governments to recognise National Assembly president Guaido as the interim president of Venezuela, and we will work constructively with them in support of his efforts to restore constitutional legitimacy.

"We continue to hold the illegitimate Maduro regime directly responsible for any threats it may pose to the safety of the Venezuelan people.

"As interim president Guaido noted yesterday: 'Violence is the usurper's weapon; we only have one clear action: to remain united and firm for a democratic and free Venezuela.'"

Did this come as a surprise?

Not really.

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The United States has had concerns about Mr Maduro's Government for some time, and when Venezuela's Congress formally declared Maduro a "usurper" last week, US Vice-President Mike Pence said he called Mr Guaido to express his support.

"The Vice-President firmly emphasised that the long-standing goal of the United States and all freedom-loving nations is to restore democracy to Venezuela through free and fair elections, and end the unprecedented humanitarian and economic crises in the once-rich cradle of Bolivar," a White House official said.

The Trump administration has also been weighing whether to levy a new round of economic sanctions against Venezuela to pressure Mr Maduro to resign.

Does anyone else agree with Australia and Trump?

Yes.

Several other countries have also declared they will recognise Mr Guaido as Venezuela's interim president.

They include Canada and a slew of right-leaning Latin American governments, including Venezuela's neighbours Brazil and Colombia.

Sorry, this video has expired Thousands take to the streets of Caracas to protest against Maduro

But politicians in Russia, which has a close relationship with Venezuela, were critical of the US move.

"I think that in this developing situation the United States is trying to carry out an operation to organise the next colour revolution in Venezuela," Russia's deputy chairman of the foreign affairs committee of the Upper House of Parliament Andrei Klimov said.

'Colour revolution' is a Russian term for the popular uprisings that unseated leaders in Georgia, Ukraine and Kyrgyzstan.

Will this change anything?

The standoff between Mr Maduro and Mr Guaido could set the scene for more violence and has plunged troubled Venezuela into a new chapter of political turmoil.

Despite some international recognition, it is the country's armed forces which are regarded as playing a vital role in restoring democracy.

"The armed forces have a fundamental role to play in the restoration of democracy," the military attaché at the Venezuelan Embassy in Washington, Col Jose Luis Silva, said in the video.

So far, Venezuela's top commanders have pledged loyalty to Mr Maduro's government in the days since Mr Guaido declared himself interim leader.

But support for Mr Maduro's rule is weaker among the military's rank and file, whose households are suffering from widespread food shortages and hyperinflation like their civilian counterparts

This also isn't the first time the US has inserted itself into Latin American politics.

It has a long history of intervening — both directly and indirectly — to change governments in South America.

For that reason, Mr Maduro warned his supporters they could not "trust the gringos".

"They don't have friends or loyalties. They only have interests, guts and the ambition to take Venezuela's oil, gas and gold," he said, rattling off a long list of US-backed military coups, including in Guatemala, Chile and Brazil.

Nicolas Maduro says Venezuela cannot trust America. ( AP: Ariana Cubillos )

Dimitris Pantoulas, a political analyst in Caracas, said discontent was spreading across the country.

"The Government is resorting to its old tricks, but the people no longer believe them," he said.

ABC/wires