The Umkhonto we Sizwe Military Association (MKMVA) has announced that it has launched its own investigation to expose all ANC MPs who supported the motion of no confidence in President Jacob Zuma.
The association says the dissident MPs are "dangerous, poisonous snakes that must be burnt".
The ANC defeated the motion, but at least 35 to 40 ANC MPs supported the motion.
"You cannot live with a poisonous snake in your house because it will kill you," its president Kebby Maphatsoe said at a press briefing on Sunday.
Maphatsoe said the historic motion, where a secret ballot was used for the first time, had shown that there was an "enemy" within the party.
"When you have a poisonous snake, you hit it hard on the head, and you burn it to make sure it is dead," Maphatsoe told journalists.
He was speaking following the MKMVA national executive committee meeting in Johannesburg. He said as the "eyes and ears" of the ANC, they will investigate who defied the party line.
"We suspect very strongly that money was used to buy ANC MPs. There is no way that 26 ANC MPs would vote against their government without being bought," Maphatsoe said.
He denied that their investigation amounted to a witch hunt. He said the investigation was necessary to avoid ANC MPs looking at each other with "suspicion and not trusting each other".
Come out and apologise
He urged MPs who voted in favour of the motion to come out in the open and apologise.
On Tuesday, the ANC said it would discipline at least three MPs who had publicly admitted to voting for Zuma to go.
Read more: ANC to discipline members who voted for Zuma to go
Maphatsoe mentioned former finance minister Pravin Gordhan, former tourism minister Derek Hanekom and MPs Mondli Gungubele and Makhosi Khoza, who said they would vote with their conscience.
He said party members had to vote with the party as South Africa did not have a constituency-based electoral system, but rather voters elected parties who then submitted names.
He supported the ANC national working committee's call to have Hanekom removed as chair of the party's national disciplinary committee.
"We have disciplined ANC councillors for voting with the opposition, and there was no noise. They are not superior. Discipline must be implemented equally."
Also read: Only NEC can replace me as ANC disciplinary chair - Hanekom
The calls for the dissident MPs to be disciplined has deepened divisions within the party, with some national executive committee members calling for a special NEC meeting to discuss the inquiry.
The MKMVA has also condemned what it called "vicious" attacks on their presidential candidate Dr Nkosazana Dlamini-Zuma by linking her to her ex-husband, Zuma.
Maphatsoe did not mention names but said the attacks were coming from within the ANC.
Last weekend, NEC member Bheki Cele denounced Zuma for campaigning for Dlamini-Zuma.
"This is the wrong campaign for people to say electing Nkosazana Dlamini-Zuma is still the same as Jacob Zuma. In the ANC, you join as an individual and not as a family," Maphatsoe said.