(Adds Comment by mayor, Unasur bloc statement, in paragraphs 23 and 27-28)
By Andrew Cawthorne and Diego Ore
CARACAS, March 12 (Reuters) - Protesters battled soldiers in the streets of Caracas again on Wednesday as three more fatal shootings raised to 25 the death toll from a month of demonstrations against Venezuela's socialist government.
Thousands of supporters and foes of President Nicolas Maduro took to the capital's streets for rival rallies marking a month since the first bloodshed in the recent unrest around the South American OPEC nation.
Violence began when National Guard troops blocked opposition marchers from leaving Plaza Venezuela to head to the state ombudsman's office. Students threw stones and petrol bombs while security forces fired teargas and turned water cannon on them.
Reuters witnesses saw dozens of people leaving injured.
In central Carabobo state, a student, a middle-aged man and an army captain were shot dead in the latest fatalities from now-daily clashes around the South American nation of 29 million people.
Opposition activists blamed armed government supporters for shooting the student near his home in Valencia city, but the state governor said the shot came from snipers among protesters.
A 42-year-old man was killed during the same disturbances, shot while painting his house, the local mayor said. In the third killing, an army captain died from a gunshot during a clash with "terrorist criminals," government officials said.
Maduro, a 51-year-old former bus driver who was elected last year to succeed the late Hugo Chavez, has declared victory over an attempted "coup" against him and does not look in danger of being toppled.
Students, though, are vowing to keep the protests going. Protracted instability could bring more bloodshed and further weaken Venezuela's troubled economy.
"I'm going to take drastic measures against these sectors who are attacking and killing the people," a furious Maduro said in a speech to the nation as night fell.
VICTIMS ON BOTH SIDES
In the first deaths on Feb. 12, two opposition supporters and a pro-government activist were shot dead in Caracas, galvanizing the fledgling protest movement and sparking clashes in the capital and some western Andean cities.
The 25 people killed include victims on both sides.
"Today we're marching to denounce the repression. There can't be impunity. Why do they attack us when we are demonstrating freely? The security forces are bowing to a political ideology when their duty is to protect the people," said law student Agnly Veliz, 22, at the opposition rally.
Veliz said she was at the fateful Feb. 12 rally and has been protesting every day since then. "What's the point of graduating while the country is in chaos? If I lose the year but help to achieve a better Venezuela, then it's worth it."
Of the more than 1,300 people arrested since the demonstrations began at the start of February, 92 are still behind bars, according to the government.
Those held include 14 security officials, some of whom are implicated in the deaths of two of those shot in the Feb. 12 rallies. More than 300 people have been injured in the unrest.
"The opposition are causing all the violence. They should think a bit smarter. The street barricades make no sense, they just bring violence," said government supporter Marcos Alacayo, 46, among hundreds of 'Chavistas' at a square in east Caracas.
"They're trying to make out the nation is in a bad state, but that just isn't true. More people have access to healthcare, education and good food than ever. That's what they don't understand. Before Chavez, no one had what we have now," added Alacayo, who works for a state-run higher education program.
Although their movement is smaller than those in Brazil, Ukraine and the Middle East, the protesters in Venezuela share a similarly amorphous list of grievances and causes.
Some want Maduro out now. All complain about crime, inflation and shortages of basic goods. Demands to free detainees, especially hardline opposition leader Leopoldo Lopez, have become an increasingly loud cry on the streets.
"Look what they're doing to us," said student Pedro Romero, showing an injury on his leg from a gas cannister in the Caracas clashes. "That's how they treat the future of this country."
As dusk fell, protesters moved to the capital's Plaza Altamira and fighting continued with security forces.
Some demonstrators broke windows and vandalized a local office block, hauling chairs and desks outside to sit in the street as piles of rubbish burned behind them. The local opposition mayor said they were infiltrators.
The protests have wrong-footed the moderate leadership of Venezuela's opposition coalition, including two-time presidential candidate Henrique Capriles, who lost to Maduro by 1.5 percentage points in last year's vote.
His strategy had been to work patiently in grassroots communities while waiting for the next electoral opportunity, parliamentary elections in 2015, but now firebrand opposition leaders and students are taking the lead.
Other Latin American nations, though deeply worried, have taken a relatively low-key approach to Venezuela's crisis.
Foreign ministers from South America's Unasur group of governments met in Chile on Wednesday and issued a statement condemning the violence in Venezuela, urging dialogue, and creating a committee to try to promote talks in Venezuela.
"Unasur expresses condolences and solidarity with the families of the victims, the people and the democratically elected government of that brother nation," it said.
U.S. Secretary of State John Kerry said Venezuela's neighbors should take the lead in helping mediate the situation, and rejected Maduro's repeated accusations that Washington was stirring up trouble against him.
"We've become an excuse. We're a card they play," Kerry told a U.S. House of Representatives committee. "And I regret that, because we've very much opened up and reached out in an effort to say, 'it doesn't have to be this way'."
Oil exports, which provide 95 percent of Venezuela's revenues, remain unaffected by the crisis. (Additional reporting by Girish Gupta and Eyanir Chinea in Caracas, Fabian Cambero in Santiago and Jim Loney in Washington; Editing by Mohammad Zargham)