Watchdog group: 591 inmates killed during 2012 in worsening violence in Venezuela's prisons

A Venezuelan watchdog group says the country's latest bloody prison clash came after a year in which 591 inmates were killed in the country's troubled prisons.

The Venezuelan Prisons Observatory released last year's death toll on Thursday, saying it was the highest it has recorded during the 14 years of President Hugo Chavez's presidency.

The number of deaths in prison riots and other violence in 2012 was up about 5 percent from the previous year, and up about 24 percent over the number killed in 2010.

Human rights groups called for a thorough investigation into Friday's violence at a prison in the city of Barquisimeto. The government reported 58 killed in clashes between inmates and troops. Nearly all of victims were inmates.