Beeld reported that Vlok, Van der Merwe, General Chris Smith and Colonel Gert Otto, who were also involved in the assassination plot, were all part of the group of 100 prisoners whose possible pardons came under the spotlight in court.
The High Court in Pretoria on Wednesday granted an interim interdict preventing President Kgalema Motlanthe from granting pardons to more than 100 prisoners convicted of politically motivated apartheid crimes.
Judge Willie Seriti ruled in favour of a coalition of civil society groups who had brought the urgent application.
The applicants had argued the granting of pardons should be set aside until the right of the victims to be heard had been fully explored.
In mid-2006, Vlok publicly apologised for his role during apartheid and washed the feet of Chikane who, as secretary-general of the SA Council of Churches, had been targeted by Vlok for assassination.
Vlok also washed the feet of the 10 widows and mothers of the "Mamelodi 10", a group of anti-apartheid activists who had been lured to their death by a police informant.
Vlok subsequently received a 10-year suspended sentence in the High Court in Pretoria in August 2007. - Sapa