A cyclone that slammed into Mozambique 4 days ago is feared to have killed up to 1,000 people.
Entire villages were submerged and bodies were floating in the floodwaters, the nation's president said.
"It is a real disaster of great proportions," President Filipe Nyusi said.
Cyclone Idai could prove to be the deadliest storm in generations to hit the impoverished southeast African country of 30 million people, the Associated Press (AP) reported.
Speaking on state Radio Mozambique, Nyusi said that while the official death toll stood at 84, "It appears that we can register more than 1,000 deaths."
Emergency officials cautioned that while they expect the death toll to rise significantly, they have no way of knowing if it will reach the president's estimate.
More than 215 people were killed by the storm in the three countries, including more than 80 in Zimbabwe's eastern Chimanimani region and more than 50 in Malawi, according to official figures. Hundreds more were reported injured and missing, and nearly 1,000 homes were destroyed in eastern Zimbabwe alone.
Doctors Without Borders said rivers have broken their banks leaving many houses fully submerged and around 11,000 households displaced in Nsanje, in southern Malawi, according to AP.
"I was indoors with my children, but when we looked we saw mud coming down the road towards the houses and we fled," Francisco Carlitos told Lusa, the Portuguese News Agency. The family lost their home and possessions but safely reached higher ground.
The country's president, who cut short a visit to neighboring Swaziland over the weekend because of the disaster, spoke after flying by helicopter over Beira and two rural provinces, where he reported widespread devastation.
"The waters of the Pungue and Buzi rivers overflowed, making whole villages disappear and isolating communities, and bodies are floating," Nyusi said.
In 2000, Mozambique was hit by severe flooding caused by weeks of heavy rain, a disaster made much worse when a cyclone hit. Approximately 700 people were killed in what was regarded as the worst flooding in 50 years.
