The Independent Electoral Commission (IEC) ruled out on Tuesday online registration as an option for the 2014 elections, saying it might put at risk the vital integrity of the voters' roll.
"The law says you have to register in person. We feel that maybe the time has not come yet, we have to give it a few more years," IEC chairwoman Pansy Tlakula told Parliament's home affairs portfolio committee.
"We need to maintain the credibility of the voters' roll as we go into elections."
Tlakula conceded that it had been called into question by problems in three by-elections in KwaZulu-Natal, notably in Vryburg in the Abuqulusi municipality, but added that she believed it was not a "widespread problem".
A by-election in Ward 22 of the municipality had to be postponed after a former ANC councillor went to court charging that names had been fraudulently added to the roll.
The IEC investigated and said it had to remove 1525 people from the roll and transfer them back to their original wards as it could not be proved that they ordinarily resided in the ward.
The matter is now before the Constitutional Court, where the parties have until August 20 to object to the matter being submitted to the Electoral Court for it to determine whether the IEC had conducted a proper investigation.
Chief electoral officer Mosotho Moepya said the controversy over the voters' roll in Zimbabwe's recent elections, where many claimed that their names had been removed from it, had highlighted the need for tight control.
"The voters' roll remains a fundamental contribution to the integrity of our elections."
Moepya said so far 23 million South Africans were registered for the 2014 national and provincial government elections and the IEC planned to hold registration weekends, as it has done in the past, because these drew a strong response.
"We hope to register another million people for the election," he said.
The elections must be held within 90 days of April 21, when the mandate of the current legislature expires.
Moepya said the IEC was committed to being ready at any point from then on to organise the poll.
The task would entail training a quarter of a million people as election staff, and ensuring that they were reliable, he said.
"It is quite fearful to think that people you train for less than 10 days will become your face. So we have to be quite careful how we select and train these people."
If an Electoral Amendment Bill is passed, the 2014 elections will see South Africans living abroad being able to vote for national government.
This amendment was drafted in response to a Constitutional Court ruling that found their exclusion from national ballots an "unjustifiable limitation" on democratic rights. Prisoners will also be allowed to vote.
The IEC declined to elaborate on how this would affect preparations for the upcoming elections. It said it would deal with the issue in committee meetings where the bill would be discussed.
Moepya said the IEC's other challenges included making voting stations more accessible and dealing with changes in some municipal boundaries.