Africa's most industrialised economy is one of the world's largest greenhouse-gas emitters, relying on coal for 80 percent of electricity generation. The fossil fuel is a bedrock of the economy, employing more than 100,000 people.

"We are in reality facing a climate challenge of emergency proportions," Ramaphosa told a meeting of government officials and international backers aimed at pushing forward plans for transition towards a more climate-friendly economy.

However, "It is crucial that the transition to a low-carbon economy is just and inclusive and that no worker or community is left behind," he said.

South Africa will decarbonise at "a pace and scale that is affordable to our economy and society," Ramaphosa said at the event, attended by diplomats, climate scientists and financiers.

Acting too fast, before alternatives were in place, risked damaging huge sections of the economy, he said.

In 2021, rich nations endorsed South Africa's plans to wean itself off coal in an $8.5-billion plan which is also meant to mitigate the socio-economic impact of transition by supporting coal-sector workers who lose their jobs.

The World Bank in 2022 granted $497 million in financing to decommission one of its largest coal-fired power plants and convert it into renewable energy.

But there has been some reluctance to move away from coal, including from within Ramaphosa's African National Congress which has a long history of support from labour unions representing mine workers.

Jobs are a crucial factor in South Africa, where the unemployment rate hovers above 30 percent.

The country has meanwhile been hit hard by insufficient electricity supply. Ageing and poorly maintained infrastructure at its state-owned electricity firm has meant major power cuts, peaking at up to 12 hours of no power a day in some parts of the country last year.

South Africa has in recent years opened up to private investment to establish a competitive electricity market, with green hydrogen and wind energy promoted as alternatives.

In his address, Ramaphosa highlighted carbon taxes on companies as an important incentive for investment in cleaner technologies.

He said the government was investing in retraining programmes to mitigate job losses from a green transition and to support small businesses.