"We're trying to come up with an emergency plan, to work out how to get people out, supplying them with medicines and clean water," said a government official in Luanda, Angola's capital and the area hardest hit by the flooding.

"There has been a lot of damage done already and Luanda really isn't prepared to deal with this kind of situation," the official said on condition of anonymity.

While heavy rains are common at this time of year, the countries are often ill-prepared to cope.

Decades of civil war in Angola and Mozambique in particular have hampered the upkeep of infrastructure, leaving the drains and flood controls in a poor state of repair.

More than 50 people died in and around Luanda -- mostly in the Cacuaco municipality -- and some 1,200 families were displaced after their houses were destroyed by torrents of water, Luanda police spokesman Divaldo Julio Martins said.

"We believe that the number of reported deaths will rise," Martins said, adding more rain was expected.

The scale of the flooding has led to fears of an outbreak of cholera or other infectious diseases.

"We're calling on the health authorities to set up cholera treatment centres in Luanda. They need to be prepared because the consequences could be very serious," said Mark van Boekel, head of Medicins Sans Frontieres Holland in Angola.

More rain will also complicate efforts to set up temporary camps for those displaced in Cacuaco, where most of the homes are built on unstable sand and earth.

Some 70 percent of Luanda's more than 4 million residents were believed to be affected or at risk from the flooding.

CROPS DESTROYED

In neighbouring Zambia, officials were scrambling to airlift relief supplies to more than 20,000 people who had fled to higher ground after floods in Zambezi and other towns in the northwest, near the border with Angola.

The rising waters devastated cassava, maize, sorghum and millet crops and destroyed bridges linking the towns.

"Crops have been destroyed due to the disastrous floods, and people urgently need relief," Richard Salivaji, the permanent secretary of North Western province, said in a news conference in the Zambian capital Lusaka.

Salivaji said many of the displaced villagers had no food.

Authorities in Mozambique, which was devastated in 2000 and 2001 by floods that killed more than 700 people, also reported that flooding had wiped out crops and killed livestock in a number of towns.

Five people died and some 5,000 were forced to flee to emergency shelters in the former Portuguese colony.

"Small rivers burst their banks and flooded our fields, sweeping away everything including our goats and chickens," Armando Casimiro, a resident of Moma in Nampula province, told Noticias, a daily newspaper in Maputo.