One week after thousands of troops stormed a riot-torn prison in Venezuela, hundreds of rebelling inmates remained barricaded inside on Friday as a bitter political blame game continued to escalate.

Security officials, whose forces stormed the El Rodeo prison complex on Friday last week after clashes killed at least 22 people, predicted an imminent surrender.

But instead of capitulating prisoners, all that was brought out of the prison's charred cellblocks in the early hours of Thursday was four dead bodies, reportedly in an advanced state of decomposition. So far the official death toll is 29, with the government blaming the violence on heavily armed "mafia" leaders, known in Venezuela's crumbling prison system as pranes.

José Argenis Sánchez, an evangelical preacher who has been attempting to negotiate a truce, said prisoners feared being killed if they surrendered. "In the past the national guard [has] killed men in prisons," he said.

Sánchez conceded, however, that gang leaders in El Rodeo were also reluctant to lose their grip on the lucrative business they controlled: selling drugs and guns and charging protection money, known as la causa.

"There are too many interests involved. They make a lot of money inside prisons. They charge inmates and they buy and sell weapons. I think the national guard has cleared out a lot of spider's webs, but they need to get to the spider."

All week tearful female relatives of inmates have flocked to El Rodeo, clutching improvised banners. "Mr President: Stop this massacre. We don't want any more dead," read one appeal to Venezuela's leader, Hugo Chávez, who remains in Cuba after undergoing emergency surgery earlier this month. Another implored: "National guard: Stop firing weapons of war at the prisoners!"

The crisis has sparked a war of words between government supporters and opposition politicians. Chávez supporters accused the opposition of inciting violence and vowed to investigate the role of "hasty" media outlets that had "manipulated" the situation.

One high-ranking government official, who refused to be named, told the Guardian: "We have strong evidence that suggests articulation between the pranes and some opposition leaders. There is an effort on behalf of the opposition to build up destabilising actions following the current jail crisis and extend it to other jails across the country."

Opposition leaders scoffed at the allegations, claiming the government was attempting to divert attention from its own failures.

Ismael Garcia, leader of the opposition Podemos party, said: "This is all a clear excuse to go after the opposition media, and an excuse not to talk about the real problems of corruption we face. Why is no one talking about how the inmates got all the weapons the national guard has seized? It wasn't just makeshift knives, it was war armament that only the national guard has access to."

Garcia, who travelled to the besieged jail on the first night of violence, said he believed El Rodeo's true death toll might never be known. There were "close to 40 to 60 family members who have not seen the names of their relatives in the published lists [of transferred prisoners] and have had no other news," he said.

Writing in the opposition El Universal newspaper, Jorge Sayegh criticised both sides for squabbling over blame instead of addressing deeper issues. "What a nerve, for the government and the opposition to attempt to wear the mask of innocence, accusing each other of [being responsible for] the murderous anarchy, which we all know predominates in the prisons. What good does it do to call for the resignation of a minister, when it is clear that the entire prison system, the police and the judiciary are rotten?"

Venezuelan jails had become "cathedrals of delinquency", he added.

On Thursday there were reports that four prisoners had been killed and three injured during shooting at Uribana prison, in Lara state.

According to one local NGO, the Observatorio Venezolano de Prisiones, 466 Venezuelan inmates were killed last year compared with a total of around 100 in Brazil, Argentina, Mexico and Colombia.