The lives of 150,000 people are in immediate danger because of continuing torrential rain and flooding in Mozambique, according to United Nations officials.

They say the families - living in the Limpopo Valley north of the capital, Maputo - have no food and little clean water, and outbreaks of dysentery are rife.

The swollen Limpopo River has swept through the town of Xai-Xai, flooding the lower-lying parts and causing panic among residents, according to Mozambican state radio.

UN Children's Fund official Ian McCleod told the BBC that flooding along the Limpopo peaked on Thursday, but levels were expected to remain exceptionally high.

He said worse was expected, with tropical storm Eline predicted to hit the area at the weekend.

The storm has already struck Madagascar, killing two people and causing extensive damage along the east coast.

Access problems

The most pressing problem is simply to reach the people in need, thousands of whom are trapped by floodwaters, according to a UN Disaster Assessment and Co-ordination (UNDAC) team.

The priorities will be to rescue those trapped by floodwaters and to deliver badly needed relief assistance to affected populations.

"We are talking at this stage of basic survival needs - food, shelter, clean water, sanitation, and the infrastructure," said Katarina Toll Velasquez, leader of the UNDAC team.

"Then we are looking ahead at what is the biggest fear, the outbreak of health epidemics. We have been expecting health problems, and these have already started.

The team is trying to map which roads and bridges are still usable.

Ms Toll Velasquez said the full scale of the disaster would become apparent within the next two to three weeks.

"There is an urgent need for contingency planning," she said.

Helicopters

She praised the assistance provided by South African helicopters taking essential supplies to remote areas, but said donor governments had to provide further funding for the air operation.

The cost could not be borne by Pretoria alone, she said, "especially in view of the fact that they are having to cope with floods across the border in their own country".

Relief assistance from abroad has included a delivery of five inflatable boats from Italy.

In addition to the exceptionally heavy rains which have fallen over Mozambique itself, floodwaters rushing down from South Africa's highlands have aggravated the situation on Mozambique's low-lying coastal plain.

Mozambique, South Africa, Swaziland and Botswana have in the past two weeks experienced their heaviest rains in 40 years.