VALENCIA, Venezuela (Reuters) - Venezuelan protester Juan Manuel Carrasco says he was cursing soldiers during an anti-government protest when they grabbed him and two friends.
In a case that has become a focus for brutality accusations against Venezuela's security forces, the 21-year-old Carrasco says he later found himself in a National Guard holding area.
"They got me on my knees and started hitting me with batons," he told Reuters at his family home in the central city of Valencia where he is under house arrest pending trial for involvement in unrest that has rocked Venezuela in recent weeks.
"They called me a son of a bitch, and said 'We're going to kill you'," he said, showing bruises on his torso and describing the actions of what he says were 30 soldiers who then forced him and 11 others to strip on February 13.
"They shoved a rifle up my bottom."
That last accusation has particularly incensed government critics, and is one of the most serious of allegations that human rights groups are levelling at Venezuela's military and police over this month's unrest.
The government, however, specifically denies Carrasco's allegation and says it is part of a campaign of fabrication to denigrate President Nicolas Maduro's government and overshadow violence by demonstrators.
At least 13 people have been killed, about 150 injured, and more than 500 arrested during protests and violence that have flared since the start of February.
"Do you think someone who's been violated, had the barrel of a rifle put in his anus, could sit for a hearing?" said the state prosecutor, Luisa Ortega Diaz, referring to Carrasco's legal proceedings after being detained.
"It's unpleasant to speak about this, but we have to. The medical-legal examination shows it is not true," she added, saying that nevertheless three soldiers had been detained and were being investigated over the allegations of beating.
MADURO DENIES TORTURE
Officials from Maduro down say Venezuela's security forces have mainly acted with restraint and patience against demonstrators despite being insulted, stoned and even shot at.
Reuters reporters have witnessed violence by some demonstrators, and also seen security forces pointing weapons and roughing up some apparently unarmed protesters.
Maduro has repeatedly shown videos on state TV of a sharpshooter firing at government supporters, and of protesters stringing wire across a road.
The president says torture ended in Venezuela with the arrival of President Hugo Chavez, his socialist predecessor and mentor, in 1999.
"Commander Chavez never gave the order to torture anyone. We came from that school of thought," Maduro said.
"If there was any evidence in any case, I'd be the first to investigate and punish it, I guarantee."
One of the main groups tracking abuse allegations, the opposition-linked Venezuelan Penal Forum, says it has used medical records to confirm 18 cases of what it calls "torture," including Carrasco's. It fears there are at least a dozen more.
Almost all are cases of heavy bruises caused by beatings.
"People don't want to speak so it's difficult for us," the group's director Alfredo Romero told Reuters.
"They detain them and beat them ... This is intimidation and torture. A student who's been in jail, been tortured, won't go to the streets again. They've learned their lesson."
Opposition supporters are posting videos and photos online that appear to show incidents of brutality but some have turned out to be footage from clashes in Egypt, Chile and elsewhere.
Some opposition leaders have gone further than local rights groups, speaking of "hundreds" of torture cases.
"This is a moribund government which the world is calling genocidal," said opposition leader Henrique Capriles, using the inflammatory language typical of politicians on both sides.
At Carrasco's fourth-floor apartment in a middle-class neighbourhood of Valencia, his mother gazes from their balcony at police trucks in the street outside.
"They're dangerous thugs," she said, backing the version of her son, who works with his father installing kitchens around Valencia. "I don't support any political party. I just want to live, to do my shopping and not get killed."
(Editing by Andrew Cawthorne, Kieran Murray and James Dalgleish)