The United Nations says the storm that has just ravaged parts of southern Africa is possibly the worst weather-related disaster ever to hit the southern hemisphere.

Around 1.7 million people were in the direct path of Cyclone Idai in Mozambique. More than 900,000 were affected in Malawi.

UN officials said storm-surge floods up to six metres deep had caused incredible devastation over a huge area.

Aid workers fear the town of Buzi could be submerged completely in the coming hours as floodwaters continue to rise.

The storm also caused widespread damage in eastern Zimbabwe where nearly 100 people have died, and in Malawi.