The British Red Cross has made an urgent appeal for donations to deal with the “severe humanitarian emergency” caused by Cyclone Idai across parts of Africa.
Authorities in Mozambique fear the death toll could be more than 1,000, while tens of thousands of people are said to have lost their homes there, as well as in nearby Malawi and Zimbabwe.
The United Nations described victims trapped on roofs and clinging to trees awaiting rescue, and said roads, bridges and crops have been washed away.
The situation is set to become even more challenging, with heavy rain predicted in the coming days, British Red Cross said.
Ben Webster, head of emergencies at the charity, said: “Cyclone Idai has wreaked devastation across a vast area. People living in the path of the storm have seen family members lost in the floods, they’ve seen their homes and livelihoods washed away. This is a severe humanitarian emergency.
“Right now the primary focus is to save lives, but the after-effects of this crisis will be felt for some time to come.”
He said the developing picture shows it is “clear this disaster will require a huge international response”.
The charity has provided 2,000 tarpaulins, 3,000 mosquito nets and 3,000 blankets from its regional warehouse in Harare to the Zimbabwe Red Cross and has released some emergency funds through its community resilience programme in Zimbabwe.
Local Red Cross volunteers are helping with search and rescue operations, the distribution of aid and facilities for temporary camps.
Concern’s Yousaf Jogezai said nearly one million people are affected in Malawi alone, where nearly 600 have been injured and more than 50 people have been killed.
Many of the survivors, whose homes have been destroyed or are submerged in floodwater, are now taking shelter in overcrowded schools and churches, where it is feared disease could spread.
Mr Jogezai said: “In some places they have hundreds of people. They don’t have enough facilities such as water or latrines. So it is posing a very serious risk, which may spread water-borne diseases such as cholera and diarrhoea, so that’s a big risk.”
He said crops which had been just one month from harvest have been completely destroyed, meaning basic necessities are urgently needed.
Noting that some communities had already been devastated by serious floods last year, he added: “They urgently need support from the international community and international organisations such as Concern to come forward and provide this life-saving assistance.”
Britain has pledged up to £6 million of aid and International Development Secretary Penny Mordaunt said a team of experts was on the ground in Mozambique helping to co-ordinate the UK’s response.
Tents and thousands of shelter kits were sent to the country on Tuesday, and Ms Mordaunt has said the UK stands ready to “scale up our support if needed”.
Concerns over the speed of the emergency response have been raised by senior Tory MPs in the House of Commons, amid warnings that lessons “were not learned” from previous crises.
Conservative former international development secretary Andrew Mitchell said the search and rescue response to the natural disaster was “much slower than in the crisis” following a previous cyclone in 2000.
He added that Cyclone Idai is heading towards being the “worst weather-related disaster to hit the southern hemisphere”.
Donations can be made to the British Red Cross Cyclone Idai appeal via www.redcross.org.uk/idai or by calling 0300 023 0811, and to Concern at www.concern.org.uk.