More than a thousand people are feared to have died in a cyclone that smashed into Mozambique last week, while scores have been killed and more than 150 are missing in neighbouring Zimbabwe.

"For the moment we have registered 84 deaths officially, but when we flew over the area... this morning to understand what's going on, everything indicates that we could register more than 1,000 deaths," Mozambican President Filipe Nyusi said in a nationwide address.

"This is a real humanitarian disaster," he said. "More than 100,000 people are in danger".

Aerial photographs released by a Christian non-profit organisation, the Mission Aviation Fellowship, showed groups of people stuck on roof tops with flood waters up to window level.

"The scale of damage... (in) Beira is massive and horrifying", the International Federation of Red Cross and Red Crescent Societies (IFRC) said.

Ninety percent of the city of some 530,000 people and its surrounding area has been "damaged or destroyed," it said in a statement.

"The situation is terrible. The scale of devastation is enormous," the IFRC's Jamie LeSueur said.

"Almost everything is destroyed. Communication lines have been completely cut and roads have been destroyed. Some affected communities are not accessible." A large dam burst on Sunday and cut off the last road to Beira, he said.

Sofala Province governor Alberto Mondlane warned that the "biggest threat we have now, even bigger than the cyclone, is floods because it's raining more and more".

Emma Beaty, coordinator of a grouping of NGOs known as Cosaco, said: "We've never had something of this magnitude before in Mozambique".

"Some dams have broken, and others have reached full capacity, they'll very soon open the flood gates. It's a convergence of flooding, cyclones, dams breaking and making a potential wave: everything's in place so we get a perfect storm."

Nyusi said the Pungwe and Buzi rivers in central Mozambique "have burst their banks and engulfed entire villages." "Communities are isolated and bodies are floating" on the waters, he said.

"Flying roofing sheets beheaded people," Rajino Paulino recounting the moment the cyclone smashed into Beira.

"We are sleeping rough, we are eating poorly and we don't have houses anymore," Paulino said.

Beira international airport was closed because of cyclone damage but later reopened.

In neighbouring Zimbabwe, Idai left 89 dead and at least 150 more missing, according to a toll compiled by AFP.

It swept away homes and ripped bridges to pieces, leaving destruction that the acting defence minister, Perrance Shiri, said "resembles the aftermath of a full-scale war".

"There was a lot of destruction both on our facilities and on people," said Shiri, speaking on television from the affected eastern highlands region.

Some roads were swallowed up by massive sinkholes, while bridges were ripped to pieces by flash floods, according to an AFP photographer.

"This is the worst infrastructural damage we have ever had," Transport and Infrastructural Development Minister Joel Biggie Matiza said.

The eastern district of Chimanimani was worst-hit, with houses and most of the region's bridges washed away by flash floods.

The most affected areas are not yet accessible, and high winds and dense clouds have hampered military rescue helicopter flights.

Two pupils and a worker at a secondary school in the area were among those killed after a landslide sent a boulder crashing into their dormitory.

Soldiers on Sunday helped rescue the surviving nearly 200 pupils, teachers and staff who had been trapped at the school in Chimanimani.

Joshua Sacco, lawmaker for Chimanimani, told AFP that between "150 to 200 people" are missing.

The majority of them are thought to be government workers, whose housing complex was completely engulfed by raging waters. Their fate was unknown because the area was still unreachable.

"We are very worried because all these houses were just suddenly submerged under water and literally washed away and that is where we have about 147 missing," he said.

Zimbabwean President Emmerson Mnangagwa cut short a visit to Abu Dhabi, saying on his return home on Monday, "we are deeply grieved as a nation".

His government has come under fire for failing to evacuate people in time.

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)