CARACAS, Venezuela — A prison riot by three rival gangs fighting for control of cell blocks left eight inmates dead and 15 injured in eastern Venezuela, officials said yesterday.National Guard troops had restored order after the riot late Monday at Puente Ayala Prison near the city of Puerto La Cruz, 150 miles east of Caracas, Gen. Jesus Bermudez said.

“Each one of the gangs wanted control of the prison,” Bermudez told the local Globovision television channel. “That’s what caused the riot.”

The injured prisoners were taken to nearby hospitals, he said.

Violence is common in Venezuela’s overcrowded and understaffed prisons, where about 20,000 inmates live in 30 facilities built to hold 15,000. Prisoners often bribe officials to obtain weapons.

Some 411 inmates were killed and 737 more were injured in 2005, according to the watchdog group Venezuelan Prisons Observatory.

Humberto Prado, director of the group, said in a telephone interview that at least 320 inmates were killed and 830 more were injured this year through October.

Prado said the government should expedite plans to “humanise” penitentiaries.

“What is the humanisation plan they have for the prisons? Because, so far this year, the violence in the jails continues and authorities haven’t taken measures to stop it,” he said.

More than 2,000 inmates at four prisons are currently staging a hunger strike to protest mistreatment by prison guards and pressure authorities to reduce sentences and guarantee quicker trials, Prado said.

Deputy Justice Minister Yuri Pimentel confirmed that inmates were staging the hunger strike, but didn’t elaborate.

He accused opposition groups of fomenting prison violence to smear the government ahead of next month’s presidential election.

“We know that a series of problems persist,” he said. “There are (opposition) groups taking advantage of very legitimate complaints among the prisoners that are trying to create chaos.”

Protests against delays in sentencing, which can leave criminal suspects languishing for years in prisons, are common in this poor South American nation.

An estimated 40 percent of prisoners have yet to be sentenced, according to the government, and in some facilities inmates have taken visitors hostage to demand their cases be dealt with more quickly.