Thousands of houses, roads, schools and health facilities were left caked in mud after being completely submerged in water from a winter storm that hit the largely rural and underdeveloped region late on Monday.

Ramaphosa, who had earlier described the floods as "unprecedented", was expected to visit the site where a school bus was swept away, killing at least six children and three adults.

On Thursday, rescuers were still going door to door searching for bodies or possible survivors, as people got stuck inside their homes when the water rushed in during the night.

Some managed to escape to their roofs, where they waited long hours for help.

Snow and heavy rainfall are common during winter in South Africa.

According to the Green Climate Fund, the country is also highly vulnerable to the impact of climate variability and change, which increases the frequency and severity of extreme weather.

The area worst hit by the floods and subsequent landslides was the city of Mthatha, about 800 kilometres (500 miles) south of Johannesburg.

On Thursday, the death toll had reached 78, Velenkosini Hlabisa, minister of cooperative governance and traditional affairs, told public broadcaster SABC News.

The South African Red Cross Society, which sent aid to the area, told AFP at least 3,500 households had been affected, with many people sheltering in community halls.

Ali Sablay, a spokesperson for disaster response charity the Gift of the Givers Foundation, said the number of people requiring assistance could increase "dramatically".

"The homes are fragile, they can collapse anytime. Food is contaminated, so people need to be evacuated," said Sablay.

At least 20 health facilities and 58 schools were damaged in the province, according to local authorities.