Hundreds of thousands of Venezuelans took to the streets yesterday to mark 50 days of protests against the unpopular government of President Nicolas Maduro, with unrest gaining momentum despite a rising death toll and chaotic scenes of nighttime looting.

At least 46 people have been killed in the worst turmoil faced by Maduro since he won the presidency in 2013.

Venezuelans from civilians to police have been killed, sometimes during increasingly frequent spates of looting or street melees.

A large opposition march in Caracas started peacefully, but by mid-afternoon had descended into violence with police in riot gear launching tear gas and stun grenades at demonstrators.

Protesters responded, hurling tear gas canisters and other projectiles back at police.

A truck was also set on fire near a highway underpass as the march passed by.

Several demonstrators were seen being detained by police, while some others were injured and taken away on stretchers.

In the unruly western state of Tachira, demonstrators were seen throwing Molotov cocktails at national guard troops. Reuters witnesses said they also saw two protesters wielding machetes.

The Andean area near Colombia suffered a week of mayhem that included looting, prompting the government to send 2,000 troops to the state.

Many Venezuelans are furious with Maduro's government, blaming it for soaring inflation, shortages of everything from food to medicine, and a crackdown on human rights.

They are demanding elections, freedom for jailed activists, foreign aid, and autonomy for the opposition-led legislature.

Major opposition marches took place across the oil-rich nation of 30 million on Saturday.

The government, which says protesters are trying to foment a coup beneath the pro-democracy rhetoric, held a counter-march in Caracas, with thousands of red-clad supporters singing and dancing.