Severe monsoon floods have stricken both countries, affecting 8.0m people in Bangladesh and 1.7m in Nepal.
In between the two areas, some 31m people are said by the United Nations to have been affected in India, in particular in Bihar state, where the Indian government is leading relief efforts.
The Department for International Development has given £400,000 to the Nepal Red Cross Society in partnership with the British Red Cross and International Federation of the Red Cross.
It has earmarked 75% of this for water, sanitation and hygiene, livelihood recovery and health and the money is expected to provide safe water supply to more than 13,000 people, give immediate food to 3,000 of those most severely affected and give health supplies to 2,000 women and girls
International development secretary, Priti Patel, said: “The UK has stepped up to support the region, our pre-positioned relief supplies ensured thousands of people received immediate support and we continue to provide assistance to vulnerable people who have lost everything.”
The department said floods occur annually during Bangladesh’s monsoon season and its government has well established response mechanisms in place, while Nepal’s government formally requested international assistance
United Nations secretary general António Guterres has said the UN is ready to further support relief efforts and that its humanitarian agencies were already at work to bring in clean water, food, shelter and medical aid for the affected areas.
The United Nations Children's Fund (Unicef) said an estimated 16m children across the region needed urgent life-saving support.
Jean Gough, Unicef regional director for South Asia, said: “Millions of children have seen their lives swept away by these devastating floods. There is a danger the worst could still be to come as rains continue and flood waters move south.”
Unicef said the situation might ultimately prove even worse, as at present many areas remained inaccessible due to damaged infrastructure and could not yet be assessed.
