The Independent Police Investigative Directorate is investigating the claims at the same time that the Civilian Police Secretariat, which is also probing the matter, said it had received more information about the allegations.
Several senior officials in the Hawks criminal unit and the South African police were last year accused of conducting the renditions, in partnership with Zimbabwean police. This has reportedly led to a number of Zimbabwean 'suspects' being arrested in South Africa and then sent across the border illegally, and killed.
These allegations were made by South Africa's Sunday Times newspaper, which reported that South Africa's Police Minister, Nathi Mthethwa, is sitting on explosive reports listing at least three deaths of Zimbabwean nationals. The deaths were allegedly as a result of a 'renditions' operation led by police and Hawks officers.
A Hawks source has recently been quoted by South African media as saying that the practice is still ongoing with at least eight of the unit's members being accused.
"They are above the law. Completely untouchable. For their work several have been promoted to senior ranks. They have links right to the top, including politicians and senior officers," the source was quoted as telling the Times newspaper.
"Several, who are from the Hawks Tactical Operational Management Services, are known to be linked to the murders of at least six Zimbabweans abducted from across Gauteng, and others have been linked to the murders of South Africans, including fellow police officers," the source said.
The renditions are alleged to have been carried out under the pretext that the Zimbabwean authorities were looking for criminals involved in armed robberies and the shooting of police officers.
Gabriel Shumba from the Zimbabwe Exiles Forum (ZEF) told SW Radio Africa that an investigation is welcome, because of the implications such practices have.
"South Africa is the first destination of sanctuary for so many people, so it is really scary and extremely worrying that South African authorities could be involved," Shumba said.
He added: "I believe this is the action of rogue and over zealous elements acting in cahoots with certain sectors of Zimbabwe's security services. This undermines South Africa's rule of law and international reputation."