Venezuelan security forces have quelled masked protesters with tear gas, water cannon and pepper spray in Caracas after blocking an opposition rally against socialist President Nicolas Maduro.

The clashes began on Tuesday after authorities closed metro stations, set up checkpoints and cordoned off a square where opponents had planned their latest protest against the government and a crippling economic crisis.

In skirmishes on backstreets and highways around the capital, youths built barricades, burned rubbish and hurled rocks and bottles at soldiers and police. Various opposition leaders organised roadblocks.

Police used pepper spray on National Assembly head Julio Borges, two-time presidential candidate Henrique Capriles and rights activist Lilian Tintori, as they led protesters onto highways and jostled at barricades, witnesses told Reuters.

Nine protesters were injured, including one who was shot in the leg, said Ramon Muchacho, mayor of one of Caracas's districts. None of the injuries were life-threatening, he said.

IN PICTURES: The crisis in Venezuela

Opposition activists said armed pro-government gangs joined the fray and opened fire.

"About 50-100 guys arrived on bikes and started to shoot in the air," protester Bernardo Sanchez told local media, saying a bullet had lodged in his thigh.

In one street, kneeling women sang the national anthem as neighbours banged pots and pans from nearby buildings in a show of anger against a government they blame for a deep recession that has led to shortages of food, medicine and other supplies.

"We're going to get rid of them but we have to fight," said Jose Zapata, 57, an electrician, as he marched with a stick in his hand.

Pro-Maduro rally

With thousands out on both sides, supporters of the 54-year-old president organised their own rally, in a volatile scenario seen constantly during the 18 years of leftist rule in the South American nation.

"They want an intervention in Venezuela," said prisons ministry worker Juan Aponte, 34, who wore the red colours of the ruling Socialist Party.

Protests also were staged in other cities and more are planned across the country for Thursday.

The government accuses opposition parties of abetting a US-led plot to topple Maduro, who has ruled Venezuela since the 2013 death of Hugo Chavez.

Tensions have soared in the country's long-running political standoff after the pro-Maduro Supreme Court last week annulled the opposition-led Congress' functions.

Although the court retracted that ruling over the weekend, the National Assembly remains powerless due to previous court judgements.

Foreign pressure on Maduro has risen as opposition protests resumed late last week.

"Here the world can see the dictatorial path Mr Maduro has chosen," Capriles said.

Maduro says the US government and other foes are whipping up hysteria against him to lay the ground for a coup.

"From the north [the United States], they give the order to the defeated fascist right of Venezuela to fill the streets with violence and blood," Maduro said on state TV.

The Organization of American States on Monday urged Venezuela to restore Congress' authority and guarantee separation of powers, but Venezuela's representative walked out, as did the envoy from fellow leftist Bolivia, which holds the OAS presidency.

"The OAS has surpassed itself in aggression against Venezuela," Maduro said afterwards. "It is a real court of inquisition, carrying out abuses and vulgarities."

Venezuela's opposition won a National Assembly majority in late 2015, but the Supreme Court has overturned almost all its measures.