Unlike the variant seen in Britain, "we haven't observed such rapid rise of the lineage in Nigeria and do not have evidence to indicate that the P681H variant is contributing to increased transmission of the virus in Nigeria".
Mr Hancock said the variant coronavirus was spreading at a "dangerous rate" as he announced the measures, which include tough restrictions on mixing with people and the closure of non-essential shops.
The travel ban comes after two cases of the "highly concerning" new virus strain had been discovered in Britain.
There is no evidence to suggest the South African variant is more transmissible, causes more severe disease or increased mortality than Britain's variant or any other variant that has been sequenced in the world, said Mkhize. He says that in the past week, Nigeria has reported a 52% increase in cases and South Africa has shown a 40% increase.
He pointed to evidence that the British strain, which bears a similar mutation to the South African one, appeared as early as September in southeastern county Kent - "approximately a month before the South African variant appears to have developed".
South Africa has identified a new variant of the novel coronavirus, which authorities believe is driving a surge in COVID-19 infections that could overwhelm its healthcare system.
Australia's New South Wales marks downward trend in new Covid-19 cases
This brings the total number of cases linked to the Avalon cluster to 104, though six of those cases came from an unknown source. "What you have today is what you will have on December 27", Premier Gladys Berejiklian said in this morning's press conference.
Britain's transport minister said he had ordered flights and arrivals from South Africa to be halted after confirmation that the mutated strain had spread to the UK.
He also said "banning travel between United Kingdom and SA is an unfortunate decision" as "the risks of travel bans may outweigh the benefits".
South Africa has so far recorded 9,68,563 cases of coronavirus cases and a total of 25,983 deaths due to the pandemic.
"But despite the obvious setback and disappointment, we are grateful that our Mum is still well and has not been affected by COVID-19, so we have convinced our children and grandchildren that the cancellation might well be a blessing in disguise and will be sending, and hopefully receiving, all our Xmas presents when couriers are allowed to resume flights next year now", Bishop said.
"What has happened with the sheer number of infections growing very fast is that's overwhelmed really fast the health care system", said Professor Tulio de Oliveira, director of the KZN Research Innovation and Sequencing Platform (KRISP), who helped conduct genome sequencing on South Africa's mutant variant.
Last week, South African health authorities identified a new variant of the coronavirus in the country. Nigeria's 7-day rolling average of daily new cases has risen over the past two weeks from 0.21 new cases per 100,000 people on December 10 to 0.40 new cases per 100,000 people on December 24.