South Africa's President Cyril Ramaphosa on Tuesday tightened restrictions, lengthening a curfew and restricting alcohol sales to control the spread of coronavirus as numbers of infections spiked over the past fortnight.

The country, the worst affected by the pandemic on the continent, has seen the daily figures for new cases double over the past two weeks, while hospital admissions have climbed by nearly 60 percent in the same period.

The spike in cases comes as the country struggles with its inoculation programme.

It announced at the weekend that it would discard two million of doses of the Johnson & Johnson vaccine following contamination concerns at one of the US drugmaker's sites.

"A third wave of infections is upon us. We have to contain this new wave of infections," Ramaphosa said in an address to the nation.

The curfew has been extended by an hour and will run from 10pm (2000 GMT) to 4am (0200 GMT), while restaurants and bars will have to close an hour before the curfew begins.

Retail alcohol sales will be restricted to daytime from Monday to Thursday.

Public gatherings will be capped at a maximum of 50 people indoors and 100 people outdoors.

"The measures we are putting in place now are appropriate to the level of risk and necessary to save lives," Ramaphosa said.

South Africa has recorded more than 1.76 million coronavirus cases since the start of the pandemic, 58,087 of which proved fatal.

Only slightly under two million people have received a vaccine dose, out of the population of 58 million people.