The UK Catholic Agency for Overseas Development, or CAFOD, said it was working with local partners to provide rice, beans, sugar, cooking oil and hygiene kits to parts of Mozambique worst-hit by Cyclone Idai.
CAFOD's country representative, Gabriel Bertani said: "There is concern for the many people cut off by the floods. Their basic needs will be clean and safe drinking water, food, medicines and shelter."
Mozambique's president said the death toll in his country could exceed more than 1,000 - although aid workers said it was uncertain at this stage whether the figure might climb so high.
Filipe Nyusi, who cut short a visit to Swaziland because of the incident, said: "It is a real disaster of great proportions".
Idai struck the Indian Ocean port city of Beira late on Thursday before moving inland towards Zimbabwe and Malawi.
Ninety per cent of Beira has suffered damaged, according to the Red Cross. Roads to the city - which has a population of half a million - have been cut off and there have also been power outages.
Emphasising the importance of a swift aid response, Gabriel Bertani from CAFOD continued: "Powerful Cyclones like Idai damage water supplies and sanitation facilities which increases the risk of water borne diseases spreading. In the low-lying areas, flood waters have caused widespread damage to crops and livestock, leaving people with very limited food for their daily needs."
Meanwhile, World Vision, the Christian children's charity, said 90,000 people had been helped through its distribution of emergency supplies in parts of Malawi affected by Cyclone Idai.
National director, Hazel Nyathi said: "Many children are traumatised after the flooding. They are scared, hungry and living without proper sanitary facilities in camps for displaced people. It is hearth-breaking."
Officials say more than 80 people have died in Zimbabwe's Chimanimani region.
Tragic loss of life in Mozambique and Zimbabwe - possibly over 1000 people have died - and widespread destruction in the wake of Cyclone Idai - praying @SouthwarkCofE for all who are suffering and all engaged in relief work: God our deliverer, come to our aid— Bishop of Southwark (@BishopSouthwark) March 19, 2019
Cyclones and tropical storms are expected in Mozambique during this time of year.
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