Venezuelan officials said Monday they are investigating the alleged killing of 28 miners in the southeastern jungle state of Bolivar.

Families say the wildcat miners were murdered Friday by members of a gang seeking to control a disputed gold claim. They say the gang threw the miner's dismembered bodies in a truck and took them away.

"We will conduct an objective, independent and impartial investigation," Venezuelan ombudsman Tarek William Saab said Monday, echoing a promise by the public prosecutor's office.

State Gov. Francisco Rangel, a staunch ally of the ruling socialist administration, denied that any massacre took place, saying local police investigated reports of a shootout, but found no bodies at the mine.

"Once again, irresponsible politicians are trying to sow chaos in Bolivar state with FALSE information about murdered miners," he wrote on Twitter, accusing opposition politicians of trying to discredit the government's campaign to root out illegal mining.

Families and people who said they witnessed the attack accused law enforcement agents of participating in the killings. Protesters on Monday continued to block the main road connecting the region to the border with Brazil.

Juan Jose Coello said he last spoke with his son on Friday, shortly before he left for the mine.

"I'm not asking for justice. Right now, I'm just asking that they return the body of my son, so I can give him a Christian burial," he told The Associated Press.

Henry Ramos, the president of Venezuela's opposition-controlled Congress, joined the families in accusing the state government of a cover-up.

"Amazing: 28 miners killed by government armed forces, and Gov. Rangel denies it," he wrote on Twitter Monday.

Other opposition politicians said the killings followed a decade-long pattern of killings in the region, and compared the case to the disappearance of 43 Mexican students in the hands of police in 2014.

The controversy comes days after the government announced a new plan to exploit mineral-rich areas in the region, where many foreign companies once operated mining concessions. Most of those projects have either been canceled or rendered inactive in recent years, according to Diego Moya-Ocampos, an analyst with the London-based consulting firm IHS Global Insight.

"The area, located in the jungle and of difficult access, has been taken over by local gangs which continue profiting significantly from illegal mining and a weak state presence," Moya-Ocampos wrote in a note to investors.