At least 45 people were killed after Monday's intensely heavy rainfall in KwaZulu-Natal flooded settlements, ravaged homes, swept away roads and displaced dozens, officials said on Tuesday.

The provincial government, which confirmed the number of dead, said in a statement the death toll could rise further and warned heavy rain would continue until evening in the coastal parts of the province.

Disaster management teams were evacuating people in areas where mudslides occurred and where buildings had collapsed, the province's department of Cooperative Governance and Traditional Affairs (Cogta) said.

Dozens of homes were washed away and several roads had caved in, hampering transportation and rescue operations. People were seen carrying some salvaged possessions to safer places as muddy waters gushed across streets.

The South African National Defence Force was asked to provide aerial support where necessary, the Cogta statement said.

The rains in KwaZulu-Natal also flooded a dam beyond capacity, making it impossible to operate a hydroelectric generator at power utility Eskom, Chief Executive Officer Andre de Ruyter said in an online briefing.

Transnet, which runs the Durban port, suspended operations across its terminals there as the deluge damaged a road and hindered access to the terminals, it said in a statement.

Floods around the coastal city of East London in January had killed at least 10 people and left hundreds homeless. Scientists suspect climate change has caused worsening floods and droughts along the eastern coastline.

The South African Weather Service declined to attribute the current spate of rainfall to climate change but said such heavy rain events could become more common.

In 2019, the Department of Environment drew up a plan for South Africa to adapt to climate change, which includes strengthening its preparedness to respond more quickly to weather disasters and help victims recover.

Heavy rainfall in KwaZulu-Natal will considerably weaken by Wednesday, the weather department said, but added rains will return from Friday to Monday.