The rains which have flooded large parts of southern Africa this week are set to continue for at least another three days, forecasters have warned.

South Africa, Mozambique, Swaziland and Botswana are experiencing their heaviest rainfall in decades, and floods have destroyed homes, roads, and crops over a wide area.

More than 70 people are reported to have died in southern Africa as a result of the floods and tens of thousands have been left homeless.

United Nations agencies have begun moblising to assist Mozambique, which on Thursday appealed for $2.7m to help 100,000 people made homeless in the area surrounding the capital, Maputo.

The UN Office for the Co-ordination of Humanitarian Affairs said donations will be used to purchase emergency supplies including inflatable boats, life jackets, life buoys, and tents.

UN agencies are also supplying food and medical needs to Mozambique, which is one of world's poorest countries.

Mozambican Planning and Finance Minister Luisa Diogo said that up to 800,000 people countrywide could be affected by floods, which are reported to have killed at least 27 Mozambicans.

Large areas in the south of Mozambique - including parts of the capital, Maputo - have turned into swamps.

All road links into the capital have been cut off, and food and drinking water are in short supply.

$100m in damage

As South Africa began to count the costs of the floods, government officials reported damages totalling more than $100m in Northern Province and Mpumalanga - the two largely rural provinces which bore the brunt of the floods.

That figure included only damage to government infrastructure, and not to private property.

Tens of thousands of South African homes have been lost, and at least 38 people are reported dead.

The worst affected are traditional mud-built houses in rural areas, and the tin shanties in informal settlements.

In Johannesburg, the Jukskei and Klip rivers both rose to eight metres above the normal level on Thursday, causing widespread flooding in the townships of Alexandra and Soweto.

South Africa's Government, already under pressure to build new homes to make up for a severe housing shortfall, now faces having to divert money to repair damaged homes.

Swazi capital hit

In Swaziland, the capital Mbabane has been without drinking water for two days. An earth tremor was reported to have damaged water mains, compounding the problems caused by the flooding.

Southern Botswana received 75% of its average annual rainfall in three days this week as the rains moved westwards.

Hundreds have been left homeless and at least one is feared dead in the usually arid country.

Police said most of the country's major roads were impassable, and the country's only railway line has been washed away in two places.