More than 100 people have died and many more are missing in Mozambique and neighbouring Zimbabwe on Sunday after tropical cyclone Idai barrelled across the southern African nations with flash floods and ferocious winds.

Authorities in Zimbabwe said the toll there had risen to 65 in the east of the country, while Mozambique said 48 people were killed in affected central areas, as the cyclone tore across the region on Friday and Saturday.

A member of parliament for Zimbabwe's Chimanimani district -- the worst hit part of the country -- gave the updated toll and added that scores remain missing, after houses and bridges were washed away by flash floods when the storm slammed the area.

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

"So far we looking at 65 people that have lost their lives," Joshua Sacco, lawmaker for Chimanimani, told AFP by phone.

"We are looking at probably 150 to 200 people missing," he said.

The majority of those unaccounted for are thought to be government workers, whose housing complex was completely engulfed by raging waters. Their fate is currently unknown because the area is 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. "It's very sad and the situation is dire."

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The United Nations in Zimbabwe said that nearly 10,000 were affected by the cyclone.

Zimbabwe's President Emmerson Mnangagwa, who cut short a visit to Abu Dhabi over the cyclone, has declared a state of disaster in the affected areas.

Government spokesman Nick Mangwana told AFP that "rescue and recovery efforts are ongoing".

Strong winds ripped roofs off of prison buildings in the southern city of Masvingo, according to state broadcaster ZBC.

Some 300 refugees who were housed at Tongogara Refugee Camp in the southeast have been affected and 49 houses damaged.

In neighbouring Mozambique where the cyclone hit first on Thursday night, the country's state-owned Jornal Domingo newspaper reported 48 people had been killed, with the deaths recorded in the worst-hit central Sofala province.

Tropical cyclone Idai battered central Mozambique on Friday, cutting off more than half a million residents of the port city Beira.