South African investigators have accused police of lying about the events surrounding the shooting deaths of 34 striking miners in the town of Marikana last year.
The Marikana Commission of Inquiry says it obtained documents that show the police force's version of events at Marikana is "not the truth" in important aspects.
The commission's spokesman, Tshepo Mahlangu, said police will be given a chance to respond.
"At this stage this information still needs to be tested," he said. "The police needs to be given an opportunity to look at the information themselves and appear before the commission, and explain certain [details] which we find very contradictory."
The spokesman said that some information presented to the commission by police may have been doctored or tampered with.
A spokesman for South Africa's police ministry, Zweli Mnisi, says the ministry's policy is to not comment on the commission of inquiry's proceedings.
"So to begin to comment now via media platforms about the findings of the commission, it will be improper because it might jeopardize the outcome of the findings," he said.
The striking miners were shot on August 16, 2012, outside a platinum mine in Marikana, after days of rising tension with police. Witnesses said police opened fire on unarmed miners. Police disputed that account, saying the officers fired in self-defense.
The shooting is considered the most severe instance of police brutality in South Africa since the end of apartheid.