President Cyril Ramaphosa on Thursday announced a two-week extension of South Africa's current national lockdown to slow the spread of the Covid-19 outbreak, warning that ending it too soon would see the disease "consume" the country.

The lockdown, which was initially set to end at midnight on April 16, will now continue until the end of the month.

"I have to ask you to make even greater sacrifices," Ramaphosa said in a televised address, after thanking South Africans for enduring being confined to their homes since 27 March.

Ramaphosa said it was clear that the lockdown, one of the strictest imposed anywhere in the world, had slowed the spread of the virus from daily increases of over 40 percent to only four percent.

"It is too early to make a definitive analysis of the progression of the disease there is sufficient evidence to show that the lockdown is working," he said.

The president gave the latest tally of infections as 1 934, and said the gains in slowing the infection rate would rapidly be lost if the lockdown was ended too soon or abruptly.

"If we end the lockdown too soon or too abruptly we risk a massive and uncontrollable resurgence of the disease ... rendering meaningless the great sacrifices we have all made.

"We are only at the beginning of a monumental struggle that demands our every resource and every effort," he said.

Ramaphosa took care to enumerate the ways in which South Africans have been impacted by the lockdown, noting that many have lost their income, and said his government would elaborate an economic response plan to deal both with the immediate impact and the aftermath of the pandemic.

"Cabinet will develop urgent economic measures to respond both to the immediate crisis and to the severe economic challenges that we must confront in the months ahead."

He stressed that once the Covid-19 pandemic was in the past, South Africa would need to see a period of "fundamental change and reconstruction" that would draw on the experience of other nations but would be "uniquely South African".

After thanking companies for philanthropic gestures, he announced that he, his Cabinet and the country's provincial premiers would take a 30 percent salary cut for the next three months, with the resultant savings to the public purse going to the national solidarity fund.

He urged other senior office bearers and captains of commerce to follow suit and donate a third of their pay to the fund.

Ramaphosa ended his address by calling on all South Africans to reach out to those who were alone and destitute during the lockdown.

"I ask that you give what you can to alleviate their burden," he said.