The disease broke out in Mexico; now officials warn of a global pandemic
Africa's first two possible cases of the potentially killer swine flu virus are being tested in South Africa.
Both women, one from Gauteng, the other from Western Cape, had "mild symptoms", said Lucille Blumberg, of the National Institute for Communicable Diseases.
It comes as the African Union prepared to establish a continent-wide response to any major outbreak of the virus.
The World Health Organization has raised the swine flu alert level to warn a global pandemic may be imminent.
The two South Africans had recently visited Mexico, epicentre of the disease, said officials.
Neither was seriously ill and one had already recovered after receiving anti-viral treatments.
But health authorities said they were unlikely to be able to confirm if one of the women did have the virus as her sample had not been stored properly.
Ms Blumberg said swine flu tests needed to be sent overseas for confirmation, as South African laboratories could still only do preliminary examinations.
Local laboratory test results are expected in days.
One of the women was named by Die Burger newspaper as 58-year-old Susan Kok, of Mossel Bay, Western Cape.
The newspaper reported that she had been feeling unwell when she returned to South Africa with her husband last Saturday, after a month-long holiday in Mexico.
"We spent quite a bit of time on trains and buses. And we were at the airport in Mexico City three times, so I thought the cough was just due to jet lag," she told Die Burger.
'A continental plan'
The African Union has been working on an emergency response to swine flu at a conference in Ethiopia.
Mexico: 168 suspected deaths - eight confirmed
US: one death, at least 91 confirmed cases
New Zealand: 13 confirmed cases
Canada: 19 confirmed cases
UK: 5 confirmed cases
Spain: 10 confirmed cases
Germany: 3 confirmed cases
Israel, Costa Rica: 2 confirmed cases each
Switzerland, Austria, Peru: 1 confirmed case each
"We hope to establish a continental plan for prevention, and if necessary a mechanism to fight this outbreak that has not yet affected Africa," the AU's Peace and Security Commissioner Jean Ping said in Addis Ababa.
Egypt has ordered the nation's quarter of a million pigs to be slaughtered over swine flu fears, in the first such move in the world, even though experts say the virus cannot be transmitted by eating meat.
The authorities in Ghana have banned imports of pork and pork products and the Central African nation Gabon has followed suit.
Health monitoring has been stepped up at ports from Kenya and Ethiopia in East Africa to Senegal and Mauritania in the west.
Mozambique has sent medical teams to its main seaports, which are some of the busiest in southern Africa.
And authorities in Nigeria, Africa's most populous country, have said they are ready to cope with any swine flu outbreak.
The WHO raised the alert to the second highest level of five on Wednesday after a Mexican child died while on a visit to the US state of Texas - the first death from the swine flu outside Mexico.
Officials put the number of suspected deaths from the bug in Mexico at 159, although just eight deaths have been confirmed.
Since the virus emerged last week, it has also spread to Canada, Europe, Israel, and New Zealand.