Violence has broken out between police and anti-government protesters as both supporters and opponents of Nicolas Maduro, Venezuela's president, staged duelling rallies in the capital Caracas.
Protesters hurled stones and police officers fired tear gas in the latest wave of demonstrations that have so far left three people dead.
About 3,000 opposition protesters dressed in white and carrying red, blue and yellow Venezuelan flags gathered on Saturday in a rich neighbourhood of the capital of the oil-rich but economically troubled nation.
They filled a plaza in Caracas' Las Mercedes neighbourhood and spilled out into nearby streets.
Most were students, who have spearheaded nearly two weeks of protests against Maduro. Rampant crime, soaring inflation and basic goods shortages are their main grievances.
Meanwhile, Maduro said on Saturday that a police manhunt was underway for Leopoldo Lopez, the hardline opposition leader who he said was behind the anti-government demonstrations.
Lopez "ordered all these violent kids, which he trained, to destroy the prosecutor's office and half of Caracas and then goes into hiding," the president told thousands of supporters at a rally in Caracas to denounce what he called a US-backed, "fascist" plot to oust him from power. "Turn yourself in coward."
In a statement on Friday, John Kerry, the US secretary of state, said: The United States is deeply concerned by rising tensions and violence surrounding this week's protests in Venezuela.
"Our condolences go to the families of those killed as a result of this tragic violence.
"We are particularly alarmed by reports that the Venezuelan government has arrested or detained scores of anti-government protestors and issued an arrest warrant for opposition leader Leopoldo Lopez.
"These actions have a chilling effect on citizens' rights to express their grievances peacefully."
Two anti-government protesters died in a rally on Wednesday, as did a pro-Maduro demonstrator in violence that raised alarms throughout Latin America and as far away as Europe. Some 60 people were injured and 100 arrested.
"Before, we would not go out on the street because of crime. Now, we go out to protest and they kill us," said university student Isaac Castillo, 27.
"We young people have neither faith nor hope. There are no jobs and even if we get one it is not enough to make a decent living," Castillo told AFP.
In downtown Caracas, government supporters wearing the bright red symbolising the leftist movement of the late Hugo Chavez and Maduro, his handpicked successor, filled several plazas.
Some protesters danced or did aerobic exercises to the rhythmic beating of drums played by their fellow demonstrators.
Protesters unfurled huge Venezuelan flags and pictures of South American liberation hero Simon Bolivar and of Chavez.
Maduro, who said Friday that he planned to attend Saturday's rally, has said the protests against him signal the rumblings of a coup to depose him. He has warned that he will use force to prevent unauthorised street demos.
Crowds of protesters have assembled in the capital in an anti-government movement launched 10 days ago by students who have received backing from some of the country's fractured opposition groups.
'Rules for television'
On Friday police used tear gas and water cannons to disperse a student rally. The movement they are spearheading poses the biggest challenge to Maduro since he won election last year following the death of Chavez from cancer.
Wednesday's violence led to a security crackdown in cities across a country where the economy has been battered by inflation of more than 50 percent.
The UN High Commission for Human Rights on Friday urged the Caracas government to bring those responsible for the violence to justice. The European Union also expressed concern.
Seeking to quell the unrest, Maduro late Friday announced a 10-point plan to crack down on crime that includes disarming the population, increased police patrols, as well as unspecified "clear rules for television."
The protesters have demanded that Maduro step down, although opposition leaders have said that political conditions are not favourable at present for the president's exit.
Despite having the world's largest proven reserves of crude oil, the country has severe economic problems and a deep divide between rich and poor.
Venezuela - with an institutionally socialist government dependent on oil revenues in a state-led system - has been hurt by a shortage of hard currency, while dwindling supplies of consumer goods have frustrated even some government supporters.
The government blames "bourgeois" local business interests for trying to profit from its largely low- and middle-income political base.