(Adds calls for protests, Maduro quotes, details)
By Brian Ellsworth and Diego Oré
CARACAS, April 20 (Reuters) - Venezuela's opposition renewed nationwide protests on Thursday to pressure President Nicolas Maduro to hold elections and improve a collapsing economy, and vowed to keep up pressure by staging three more protests in the next four days.
Thursday's crowds were smaller than the hundreds of thousands of people who flooded the streets of Caracas and provincial cities on Wednesday, the latest and largest in several weeks of protests against what Maduro's opponents condemn as a lurch toward dictatorship.
But still, thousands of people waving Venezuelan flags and shouting "No more dictatorship" took to the streets in the capital and across the oil-rich nation.
The opposition's leadership then called for further protests in communities across Venezuela on Friday, a white-clad "silent" march in Caracas on Saturday to commemorate the eight people killed during unrest this month, and a nationwide "sit-in" blocking Venezuela's main roads on Monday.
That sets the stage for prolonged disruption in volatile Venezuela, where security forces have been blocking rallies this month and protests have dissolved into clashes with rock-throwing youth.
"Today the people of Venezuela showed they are committed to this cause," said opposition lawmaker Freddy Guevara during a news conference late on Thursday, urging people to stay on the streets.
Government officials dismiss the protests, characterized by street barricades and clashes with security forces, as violent and lawless efforts to overthrow Maduro's leftist government with the backing of ideological adversaries in Washington.
The opposition counters that Maduro, deeply unpopular as Venezuelans grapple with triple-digit inflation and shortages of food and basic consumer goods, is seeking to stay in power indefinitely by barring opposition leaders from office and quashing independent state institutions.
"Protests will need to grow and persist over the coming weeks to force a political transition," Eurasia analyst Risa Grais-Targow said in a note on Thursday.
"The opposition's response to regional elections, which the National Electoral Council will probably call in the coming days, will be key to maintaining momentum in the streets."
The current wave of marches, the most sustained protests against Maduro since 2014, has sparked regular melees. There were also late-night barricades and some looting in Caracas' middle-class neighborhood of El Paraiso on Wednesday night.
Two students and a National Guard sergeant were killed in Wednesday's demonstrations, bringing the death toll in demonstrations this month to eight. Rights group Penal Forum said more than 500 people were arrested in relation to Wednesday's protest and 334 remained in detention.