Dams can hold back the walls of water no longer

As desperate airlift continues, areas that have so far escaped face disaster as floodgates are opened

Areas of Mozambique so far spared flood and cyclone damage were facing the threat of waves of water last night because more dams in neighbouring countries - overflowing after a month of heavy rain - had no choice but to open their floodgates.

Areas of Mozambique so far spared flood and cyclone damage were facing the threat of waves of water last night because more dams in neighbouring countries - overflowing after a month of heavy rain - had no choice but to open their floodgates.

But officials in the capital, Maputo, said the weekend catastrophe in Chokwe - a town of 40,000 people that was submerged by the Limpopo river in a matter of hours - is not expected to be repeated.

Chokwe was situated in the southern Gaza province, which during all of February has borne the brunt of heavy rains and flooding. The new danger areas - especially the Save and Zambezi river valleys, which are downstream from large dams - reach the Indian Ocean further north. Zambia said yesterday that it was opening spillgates at the Kariba dam and Zimbabwe has already done so at the Mutirikwi dam.

The Cabora-Bassa dam on the Zambezi river in Mozambique is already full.

On the ground in southern Mozambique, South African air force helicopter crews, which have worked around the clock for more than two weeks, will today resume aid flights.

These were interrupted on Sunday when a flood wave roared down the Limpopo from South Africa, finally devastating an already swamped area, including Chokwe. In less than 24 hours the five South African helicopters airlifted more than 2,000 people to safety, half of them children.

The Maputo government urged private boat owners in the capital to join the rescue operation yesterday. It has already been enhanced by a £625,000 cash injection from Britain to fund the South African effort and two additional helicopters from Malawi. Oxfam has sent five rubber dinghies but hundreds more are needed.

World Food Programme (WFP) officials said yesterday at least 350 people had died and some 650,000 had been left homeless after three weeks of rain in Mozambique, South Africa, Zimbabwe and Botswana and the passage of Cyclone Eline last week.

Not only have people been left homeless and at the mercy of a malaria outbreak three times more severe than in an ordinary rainy season, but they have lost all their crops and most of their livestock. All main roads and bridges have been washed away in an area the size of the Netherlands, just 60km north of Maputo. The Mozambique National Disaster Agency, co-ordinating relief efforts with the United Nations, indicated that the Chokwe disaster had put an untold further number of people in danger since the WFP made its calculations.

Yesterday along the Limpopo and near the former Indian Ocean tourist town of Xai-Xai, thousands of people were still stranded on rooftops and in trees.

The agency said: "As water levels are continuing to rise, those unable to get to higher ground are at risk of drowning. The first priority is to try to get as many people to safety as possible and to get food, water and blankets to those who are safe but isolated."

In South Africa, the media raised fears of a refugee flood, though the government would not say if reception centres were being prepared. The South African Defence Minister, Patrick Lekota, is travelling to Mozambique today.