A woman carrying a baby on her back walks past damaged school in Beira, Mozambique. The United Nations is making an emergency appeal for $282 million for the next three months to help Mozambique start recovering from the devastation of Cyclone Idai. Picture: Themba Hadebe/AP

Beira, Mozambique - About 1.85 million people have now been affected by Cyclone Idai and its aftermath in Mozambique alone, UN humanitarian agency OCHA said on Tuesday, as aid workers raced to fathom the scale of the disaster and determine what help is most urgently needed.

"Some will be in critical, life-threatening situations. Some will sadly have lost their livelihoods, which whilst an appalling tragedy is not immediately life-threatening,” OCHA coordinator Sebastian Rhodes Stampa said.

Idai flattened homes and provoked widespread flooding when it made landfall near the Mozambique port city of Beira on March 14. It then ripped through neighbouring Zimbabwe and Malawi.

At least 686 people have been killed by the storm and its aftermath across the three countries, a figure that could rise as relief workers prepare for what they say are inevitable outbreaks of diseases including malaria and cholera.

Mozambique remains the hardest hit by the humanitarian crisis with tens of thousands of homes destroyed and hundreds of thousands displaced across an area of some 3,000 square km - roughly the size of Luxembourg.

"We can determine the size, we can't determine the circumstance. So we're now going out on the ground, dropping people off from helicopters to determine what the critical needs are," Stampa said. 

Reuters