The ANC has given ANC MP Derek Hanekom ten days to give reasons why he should not be removed as chairperson of the party's disciplinary committee, the ANC announced on Sunday night.
In a letter, the party says the action against Hanekom is due to his tweets on 7 August before the vote of no confidence against President Jacob Zuma.
He tweeted: "Dispel this notion of 'voting with the opposition'. We must vote against state capture, massive looting and corruption. Vote for change..."
He further tweeted: "Secret ballot. No retribution because no one will know how you voted. But this must be a vote against state capture!"
The ANC says that as chairperson of the disciplinary committee, Hanekom's tweets "detract from the independence and level of integrity expected of you in that capacity.".
Hanekom told News24 on Sunday night that he would not comment on the matter.
"I have no comment. You might wish to ask the office of the SG [Secretary General] for comment, but as far as I am concerned, this is an internal ANC matter and I will not comment on it," he said.
Hanekom has been a vocal critic of President Jacob Zuma and has twice led attempts to have him removed at National Executive Committee level within the part.
On Sunday, Hanekom addressed the United Democractic Front's 34th birthday event in Cape Town on Sunday.
According to eNCA, Hanekom said:
"The ANC must be united for the right things. The ANC must be united in standing up against the wrong things. That is the kind of the ANC that the masses are looking for," he said.
"Ordinary people are looking for the ANC that they can look up to. The ANC that will unite all the society not just itself. We're looking for the ANC which will lead society. But to lead society we as leaders of the ANC have to be held at the highest regard."