South Africa now has 709 confirmed cases of Covid-19, up from 554 cases the previous day, health minister Zweli Mkhize said on Wednesday.

The rise represents a 28 percent day-on-day change, compared with the previous 38 percent day-on-day increase.

"The largest increases will be Gauteng (province) with 64 overnight," Mkhize said on public broadcaster SABC.

South African President Cyril Ramaphosa on Monday night announced a nationwide 21-day lockdown from midnight on Thursday to try and curb the spread of Covid-19.

In an address broadcast live on television, Ramaphosa said all people in South Africa would be compelled to stay at home, save for essential services such as health workers in the public and private sectors, emergency personnel and those in security services such as the police, traffic officers, military medical personnel and soldiers.