Young Venezuelan protesters have lobbed bottles and bags of faeces at soldiers who were fighting with tear gas to block the latest march in over a month of nationwide protests against socialist President Nicolas Maduro.

Key points: Officials accuse protesters of breaking chemical weapons treaties by using faeces

Officials accuse protesters of breaking chemical weapons treaties by using faeces Two more people are killed in the latest protests, bringing the death toll to at least 39

Two more people are killed in the latest protests, bringing the death toll to at least 39 Hundreds of thousands of people have taken part in the protests that kicked off in April

The extraordinary scenes — in what was dubbed "the Shit March" on the main highway through Caracas — came as thousands of opposition supporters again poured onto the streets decrying Venezuela's economic crisis and demanding elections.

"These kids live in a dictatorship," said Maria Montilla, 49, behind lines of youths with masks, slingshots and makeshift wooden shields.

"They have no other option but to protest however they see fit."

'Poopotov Cocktails' are readied to be launched at soldiers. ( Reuters: Christian Veron )

Many carried stones and so-called "Poopootov cocktails" — faeces stuffed into small glass bottles — that they threw when National Guard troops blocked their path, firing tear gas and turning water cannons on the crowds.

"There's nothing explosive here. It's our way of saying, 'Get lost Maduro, you're useless!'" said one young protester, who asked not to be named, between tossing bottles of faeces.

In response, the Government accused the Opposition of breaking international treaties on biological and chemical weapons by throwing faeces.

Two more Venezuelans were killed in the latest round of protests — a 27-year-old man and a 32-year-old male taxi driver — government officials said.

Sorry, this video has expired Demonstrators clash with riot police in Caracas, Venezuela (Image Reuters: Carlos Garcia Rawlins)

At least 39 people have died in the unrest since early April, including protesters, government sympathisers, bystanders, and security forces. Hundreds have also been injured and arrested.

Sorry, this video has expired Former Venezuelan Supreme Court adviser Dr Raul Sanchez Urribarr discusses the protests.

The Government maintains that opponents are seeking a coup with US encouragement, but the opposition, which enjoys majority support after years in the shadow of the ruling Socialist Party, says authorities are denying a solution to Venezuela's crisis by thwarting a referendum, delaying local elections and refusing to bring forward the 2018 presidential vote.

They are seeking to vary tactics to keep momentum going and supporters energised.

Mr Maduro is seeking to create a new super body called a "constituent assembly", with authority to rewrite the constitution and shake up public powers, but critics dismiss it as an attempt to keep the socialists in power by establishing a biased new assembly.

"They closed all the democratic doors," said opposition leader Henrique Capriles, joining protesters on the highway.

"We warned how dangerous that would be for our country."

The protests so far have failed to garner massive support from poorer, traditionally pro-Hugo Chavez — Mr Maduro's predecessor — sectors of Venezuela's 30 million people.

But a bigger cross-section of society has been apparent at recent marches, some of which drew hundreds of thousands.

Hundreds of thousands of people have turned out to protest against Mr Maduro. ( Reuters: Carlos Garcia Rawlins, file )

Reuters/AP