In a major show of force, hundreds of National Guardsmen in riot gear and armoured vehicles prevented an "empty pots march" to protest now-chronic food shortages from reaching Venezuela's Food Ministry on Saturday.

In another development, President Nicolas Maduro's socialist government celebrated an Organization of American States declaration supporting its efforts to bring a solution to the country's worst political violence in years, calling it a diplomatic victory.

The United States, Canada and Panama were the only nations to oppose the declaration.

The meddling minority against Venezuela in the OAS, Panama, Canada and the U.S., is defeated in a historic decision that respects our sovereignty," government spokeswoman Delcy Rodriguez tweeted.

Later Saturday, several hundred student protesters trying to block streets with barricades skirmished with tear gas-firing riot police in Caracas's wealthy Chacao district in what has become a nearly daily ritual. There were no immediate reports of injuries as motorcycle-mounted riot police, taunted from apartment buildings, chased protesters through darkening streets.

'There's nothing to buy ... There's no beef, there's no chicken.'- Zoraida Carrillo

Earlier, more than 5,000 protesters banged pots, blew horns and whistles and carried banners in the capital to decry crippling inflation and shortages of basics including flour, milk and toilet paper. Similar protests were held in at least five other cities.

All over Venezuela, people spend hours every week queuing up at supermarkets, often before dawn, without even knowing what may arrive.

"There's nothing to buy. You can only buy what the government lets enter the country because everything is imported. There's no beef, there's no chicken," said protester Zoraida Carrillo, 50.

The capital's government-allied mayor had refused the marchers a permit to hold the "empty pots" rally, leading opposition leader Henrique Capriles to accuse authorities of trying to criminalize" peaceful protests.

"Nicolas [Maduro] is afraid of the empty pots of our people. He mobilizes hundreds of soldiers against empty pots," he said of the man who defeated him by a razor-thin margin in April presidential elections. Capriles also reiterated opposition complaints that the government is sending "functionaries and groups of paramilitaries — which they have armed — to put down protests."

Weeks of protests

Maduro has faced several weeks of daily student-led protests across the nation that he claims are an attempt by far-right provocateurs to overthrow him. They have been joined by mostly middle-class Venezuelans fed up with inflation that reached 56 per cent last year and one of the highest murder rates in the world.

Late Friday in Washington, the OAS approved a declaration that rejected violence and called for justice for the 21 people the government says have died since Feb. 12 in street protests. The declaration offered "full support" for a government peace initiative that the opposition has refused to join until dozens of jailed protesters and an opposition leader are freed.

Twenty-nine countries voted in favour of the declaration after 15 hours of debate spread over two days. After Panama sought discussion of the crisis in the body, Venezuela broke off relations and expelled its ambassador and three other diplomats.

The objections from Washington and Panama attached to the declaration were longer than the declaration itself. They argued that it violated OAS rules by taking sides.