CARACAS, Venezuela (AP) — The number of killings inside Venezuela's notoriously violent prisons has increased this year even as President Hugo Chavez faces mounting pressure to curtail the violence as he campaigns for re-election, according to a human rights group.

Riots and clashes between rival gangs in Venezuelan prisons left 304 dead inmates during the first half of 2012, a 15 per cent increase compared to the same period last year, according the Venezuelan Prisons Observatory, which tracks the violence.

Prison violence killed 264 inmates in the first six months of 2011, and a total of 476 prisoners in all of 2010, according to the watchdog group.

Prison violence continues to rise because "the policies the government has implemented and all the work that has been done has not focused on protecting the lives of inmates", said the group's director, Humberto Prado.

Prison unrest and overcrowding within Venezuela's 33 prisons have become major problems for Chavez's government. Violence is common inside Venezuela's prisons, where inmates obtain weapons and drugs with the help of corrupt guards.

Following last year's deadly armed uprising at El Rodeo I and El Rodeo II, prisons located just outside the capital of Caracas, Chavez announced plans to restructure the country's troubled penitentiary system and ordered authorities to move many of the inmates from the two prisons to El Rodeo III, an adjacent lockup.

The socialist leader promised to improve living conditions inside the country's prisons and speed up trials for inmates who have not been sentenced.

The president also created a new ministry dedicated exclusively to resolving prison-related problems and appointed Iris Varela, a former ruling party lawmaker, to take charge of the government's initiatives.

Opposition presidential candidate Henrique Capriles has strongly criticised the government's failure to stem prison violence and vowed to significantly resolve the problem if he defeats Chavez in the upcoming election.

Capriles has proposed to reduce the violence by building new prisons while expanding the capacity of existing ones, separating prisoners accused of nonviolent crimes from their violence-prone counterparts and rooting out widespread corruption among guards who often takes brides to provide inmates with drugs and firearms.

Yesterday, relatives of inmates languishing inside El Rodeo III said guards have recently attacked the prison's 650 prisoners, shooting rubber bullets at them and battering them with wooden clubs and metal tubes, causing numerous injuries.