Heavy rains and storms have battered the two southern African countries for weeks, claiming more than 30 lives in South Africa's northeastern Limpopo and Mpumalanga provinces.

Rivers burst their banks and swallowed entire neighbourhoods in several regions of Mozambique, displacing thousands including a woman who was forced to give birth on a roof as she sheltered from flood waters.

"I classify the disaster as a national disaster," the head of South Africa's National Disaster Management Centre Elias Sithole said in a statement Sunday.

Authorities continued to search for survivors and recover bodies at the weekend, but flooding had started receding in some areas, including the famed Kruger National Park, which had been forced to close and evacuate guests Thursday.

"Day visitation to the park will resume as of tomorrow," South African National Parks announced on social media, still urging visitors to "exercise caution".

- Baby born on a roof -

In Mozambique, rescue efforts were slow to reach survivors who sheltered on roofs and in trees.

At least eight people had died in the country since December 21, according to official data, but numbers were expected to rise as more people were declared missing.

A resident of Gaza province north of Maputo, Chauna Macuacua, told AFP that her sister-in-law had given birth on a roof where the family was waiting to be rescued since Thursday.

"We've been here for 4 days. My nephew was born yesterday around 11 PM (2100 GMT), and we still haven't had any rescue or assistance for the baby and mother," she said.

Wilker Dias, the director of a civil society group called Plataforma Decide, said he had received reports of several people missing.

"I think the numbers of dead will increase in the next hours," he told AFP.

South Africa also dispatched rescue teams to southern Mozambique Sunday after a car carrying five members of a South African mayoral delegation was swept away by floodwaters in Chokwe, 200 kilometres (124 miles) north of Maputo.

According to the latest figures released by the Mozambican government on Friday, more than 173,000 people had been affected by the floods across the country.