(Adds arrest order for opposition leader, situation on Thursday)
By Daniel Wallis and Brian Ellsworth
CARACAS, Feb 13 (Reuters) - Venezuela's government and the opposition traded accusations on Thursday after at least three people were shot dead in the worst unrest since protests last year that followed President Nicolas Maduro's narrow election victory.
Almost a year after the death of socialist leader Hugo Chavez, the bloodshed on Wednesday was the latest demonstration of the OPEC nation's deep polarization and the mutual mistrust between both political camps.
Three people were shot dead after pro- and anti-government marches in Caracas. Maduro said another person was in critical condition, and he blamed "small fascist groups" that he said infiltrated the opposition protest.
"They want to topple the government through violence," Maduro said on state television. "They have no ethics, no morals ... We will not permit any more attacks."
A government official said 23 people were injured, 25 arrested, four police vehicles torched and some government offices vandalized. Some opposition protesters, many with their faces covered, threw stones and burned tires in the streets.
Using the slogan "The Exit", meaning Maduro's departure from power, hardline opposition groups have been holding mostly small protests around the country for the last two weeks, complaining about crime, corruption and the fast-rising cost of living.
Leopoldo Lopez, an opposition leader who has called on his supporters to take to the streets, said the government planned the bloodshed to try to discredit his peaceful movement.
Local media said on Thursday a judge had issued an arrest warrant for him on charges ranging from instigating crime to murder and terrorism, though that could not be confirmed.
"The government is playing the violence card, and not for the first time," Lopez, a 42-year-old U.S.-educated former mayor of a Caracas district, told Reuters TV after the shootings.
"They're blaming me without any proof ... I'm innocent. I have a clear conscience because we called for peace," he said, adding that the demonstrations would continue.
"We won't retreat and we can't retreat because this is about our future, about our children, about millions of people."
Lopez's aides said on Thursday he was preparing a response to the reported arrest warrant, and would not give his whereabouts. He lives in a wealthy district of Caracas.
The protests have exposed differences within the opposition's leadership, with some favoring a more moderate approach and saying marches which turn violent only play into the government's hands as it accuses them of being "saboteurs."
INJURIES AND ARRESTS
Maduro, a 51-year-old former bus driver and union activist, has staked his presidency on maintaining Chavez's leftist legacy.
He says opposition extremists want to recreate the situation in 2002, when huge street protests led to a coup that briefly ousted Chavez. He returned to power with the help of loyal soldiers and hundreds of thousands of "Chavistas" who took to the streets to protest the coup.
There have been no signs that the current melees could topple Maduro.
Opposition and government supporters took to social media to blame their foes for Wednesday's bloodshed.
The opposition blames armed pro-government militant groups known as "colectivos" for attacking dozens of their marches over the years, scattering their supporters and spreading fear.
"The colectivos are coming!" was a cry heard several times at the opposition's latest rally, prompting some demonstrators to flee for the safety of a nearby Metro station.
One of the dead was a well-known colectivo leader from the militantly "Chavista" January 23 neighborhood of Caracas.
Two spokesmen for the colectivos appeared on state TV late on Wednesday to call for calm and demand Lopez face charges.
Sporadic political protests have become common over the last decade, but they usually fizzle out within days as residents grow tired of blocked streets and the smell of burning tires.
On Thursday morning, the streets of Caracas were quieter than usual, with some residents staying at home, but there were no reports of continued trouble.
Wednesday's outburst of violence could point to a widening rift between opposition hardliners and those who favor returning to addressing bread-and-butter issues such as poor services, widespread corruption and one of the world's worst murder rates.
Opposition moderates note that their biggest successes, such as turning pro-Chavez strongholds into opposition territory, have resulted from leaders stepping away from theatrical street protests to focus on voters' daily concerns. (Additional reporting by Caracas bureau reporters; Editing by Andrew Cawthorne and Chizu Nomiyama)