The two have been subpoenaed to testify at the special TRC hearing on the State Security Council, the now-defunct body which had the responsibility of drawing up national security policy during the height of the apartheid conflict.
They are due to be followed on Wednesday by former National Party cabinet ministers Roelf Meyer and Leon Wessels.
The TRC's probe into the SSC comes after last week's armed forces hearing in Cape Town, when high-ranking officers of the apartheid security forces were questioned at length on the chain of command which led to gross human rights abuses.
Former police commissioner General Johan van der Merwe, who has applied for amnesty, told the TRC last week that while the SSC never ordered unlawful actions, its members were certainly aware they were being carried out by the security forces.
"If it is denied that the previous government, specifically the SSC, did not have knowledge of certain unlawful actions, that is not true," he said.
He acknowledged that the words "eliminate" and "neutralise" had been used in official SSC documents when describing how anti-partheid activists should be dealt with, but said he had always understood them to mean to "arrest" and "detain".
However, high-ranking subordinates such as Brigadier Willem Schoon, former head of the security police's C-Section, which included Vlakplaas, said the words had only one meaning - to kill.
TRC deputy chairman Dr Alex Boraine told Sapa on Monday the SSC hearing would be crucial to the commission's understanding of how orders were communicated from the politicians to the security forces.
"We have studied the SSC documents very carefully. There does seem to be clear contradictions about what certain words meant. We would like to clarify that.
"It is time to move away from word games and semntics," he said.
"We are hoping that the evidence we hear this week will provide that bridge between the generals and the politicians. We have a reasonably good chance of getting clarity at long last on the chain f command."
Boraine said the evidence emerging from this week's hearing could lead to more questions being posed to former state president FW de Klerk and others.
De Klerk's predecessor, PW Botha, was also subpoenaed to attend the hearing but the TRC agreed to postpone his testimony to a later date while he recovers from a recent operation.
Some observers, like Brigadier Bill Sass, the eputy director of the Institute for Security Studies, believe this week's hearing will not produce the results the TRC is looking for.
"They are trying to find out information about things that would not have been discussed in a general (SSC) hearing," he told Sapa.
"That sort of discussion would have taken place in a small group between one or two ministers."
Although he believed the hearing would provide valuble insight into the workings of the SSC, it was likely that it would degenerate into an argument about the meaning of different words.
"There's going to be disagreement on the meaning of third force and the words eliminate and neutralise," he said.
Working against the TRC was the absence of a security forces expert on the commission to properly evaluate the evidence being heard, Sass said.