"No one doubts that inspections are necessary procedures to guarantee prison conditions in line with international standards, but they can't be carried out with the warlike attitude as (authorities) have done it," said Humberto Prado, an activist who leads the Venezuelan Prisons Observatory, a watchdog group. "It's clear that the inspection wasn't coordinated or put into practice as it should have been. It was evidently a disproportionate use of force."
In 2011, when Chavez had been in office for 12 years, he created a cabinet-level ministry to focus on prisons and appointed Varela to lead it. The president made that decision following a deadly, weekslong armed uprising at the prisons El Rodeo I and El Rodeo II outside Caracas.
Chavez at the time acknowledged that his government's previous initiatives to improve the prisons hadn't worked, and he pledged changes including building new prisons, improving conditions and speeding trials. Since then, Chavez has approved funds to repair and renovate prisons.
But opponents and activists say the government hasn't made real progress at penitentiaries where hundreds continue to die each year.
Violence has flared repeatedly at other prisons in the past year. In August, 25 people were killed and 43 wounded when two groups of inmates fought a gunbattle inside Yare I prison south of Caracas.
Venezuela has 33 prisons built to hold about 12,000 inmates. Officials have said the prisons' population is currently about 47,000.
Uribana prison was built to hold about 850 inmates. Varela said that when the violence erupted the prison held about 2,400.
Opposition leader Henrique Capriles called government officials' response "incredible" and inadequate. Without mentioning Vice President Nicolas Maduro by name, Capriles criticized government officials who ordered an investigation and then traveled off to a summit in Chile.
He noted that in Brazil, President Dilma Rousseff reacted differently after a nightclub fire that killed more than 230 people, when she cut short her summit trip and returning to visit the injured.
"Here, they go away to a summit. They dispose of it as if it were one more matter, one more little problem," Capriles said at a televised event. "If we have a state that's not capable of providing security within a penitentiary, what's left for common citizens?"
"The problem that we're seeing can't be solved closing a prison," Capriles said. "The way to solve it is resolving the problem of overcrowding."
Associated Press writer Vivian Sequera in Bogota, Colombia, contributed to this report.