The launch of a "Vote No!" campaign flies in the face of decades of educating South Africans about their right to vote, says the defence minister.
Those calling on voters to spoil their ballots in next month's elections are being "irresponsible and treacherous", government said on Monday.
Responding to a question on the planned launch of a spoilt-vote campaign by some former government leaders, Defence Minister Nosiviwe Mapisa-Nqakula said this flew in the face of 20 years of educating South African about their right to exercise their vote.
"I think it is irresponsible and treacherous for anyone to come out and say ... our people should spoil their vote."
Speaking at a justice, crime prevention and security cluster media briefing in Pretoria, she said spoiling a vote was "a betrayal of everything we fought for in this country".
Former intelligence minister Ronnie Kasrils is planning to launch a "Vote No!" campaign on Tuesday.
He will be joined in this venture by former deputy health minister Nozizwe Madlala-Routledge and a number of ANC veterans.
Protest against corruption
The campaign would call on voters to come out and vote by either spoiling their ballots, or to vote tactically in protest against corruption and current government policies.
Speaking at Monday's briefing, Police Minister Nathi Mthethwa said government had put measures in place to ensure a safe and secure election on May 7.
"Government will not tolerate any form of violence, intimidation, incitement, public disorder, vandalism or intolerance. Government will deal with anyone who seeks to derail the election process," he warned.
Several election "hotspots" had been identified, and an interministerial task team would visit these, starting this week "and interact with communities in those areas".
He later identified Bekkersdal in Gauteng and KwaMashu in KwaZulu-Natal as two such areas.
Mthethwa also announced that the South African Police Service would deploy its members around the country, as had been done in previous elections.
"The scale of deployments at each voting station will depend on how each area has been characterised as a hotspot."
Mthethwa said among those organisations invited to observe the elections were the African Union, the Commonwealth, European Union, the Southern African Development Community and the United Nations.
He also appealed to South Africans who had uncollected IDs at the department of home affairs to go and collect them.
"We wish to make a special appeal to all South Africans not to wait until the last minute and to act immediately to prevent disappointment. Home affairs has 122 000 uncollected IDs and 23 000 uncollected smartcard IDs."
Mthethwa also said there were 155 000 prison inmates across the country who were registered to vote.
There were also about 26 000 South Africans living abroad who had registered to vote on April 30. – Sapa