Everything possible was done to ensure it could not be determined how individual MPs voted in the motion of no confidence in President Jacob Zuma, Parliament said on Wednesday.

"Parliament wishes to reaffirm that all the necessary measures were put in place to ensure that the integrity of the secret ballot is not compromised, thereby making the identity of the voter impossible to trace," spokesperson Moloto Mothapo said in a statement.

Before the debate on the motion got underway, there were concerns that the ballots might be numbered. As the MPs voted alphabetically, this could be used to identify who voted which way.

Mothapo said the only printing on the ballot papers was an authentication stamp and a simple question with a choice of three options against which to make a mark: no, yes or abstain.

"To further ensure maximum secrecy of the process, no gadgets were permitted in the voting booth, photojournalists with zoom lens cameras were requested to vacate the gallery and chamber broadcast camera controllers were ordered not to focus on voting booths."

Democratic Alliance (DA) leader Mmusi Maimane ventured to a voting booth with a cellphone in his hand, but had to put it back after an African National Congress (ANC) MP drew attention to it.

Mothapo was responding to concerns about the vote which took place on August 8.

Violation of Constitution

On Monday, the Council for the Advancement of the South African Constitution (Casac) expressed its concern about the “blatant threats” being directed towards 40 or so ANC MPs who apparently voted in favour of the motion.

Their identities should not be known, it said.

"Accordingly, any act of reprisal or retribution, including internal party disciplinary action would have no basis in fact or law, and may in fact constitute a criminal offence under the Powers, Privileges and Immunities of Parliament and Provincial Legislatures Act of 2004, which exists to protect the independence and freedom of expression rights of MPs," Casac said in a statement.

"Equally importantly, any such action against any MP would constitute a serious violation of the Constitution."

Casac said National Assembly Speaker Baleka Mbete had said, when she announced the vote would be secret, that any action a political party took against an MP who voted in accordance with their conscience may be struck down for violating the Constitution.

Mothapo said the ballot boxes were stored under lock and key after the vote and may only be opened by order of the National Assembly Speaker or a court of law.

"The rigorous confidentiality measures regarding the motion of no confidence were endorsed by all parties and are similar to those employed in the election of the president and presiding officers since 1994," he said.