Torrential rain in the northern and southeastern parts of Bangladesh has put more than 4 million people at risk of food insecurity and disease, said the International Federation of Red Cross and Red Crescent Societies (IFRC).
Floods and landslides have damaged roads and vital infrastructure leaving hundreds of thousands stranded and without power and electricity. More than 66,000 homes have been destroyed, according to IFRC.
Food and clean water shortages are being reported, as well as a rise in waterborne diseases, it said.
"These communities are reeling under the full force of the monsoon rain and the ensuing floods and landslides. Even if the rain recedes, overflowing rivers upstream will worsen the flooding in the coming days," said Azmat Ulla, the head of Bangladesh Office of the IFRC.
Food crops are under threat of being wiped out by floods across major farming and agricultural lands. There are fears that destruction of crops may lead to food shortages. Those most at risk include children, breastfeeding mothers, pregnant women, and the elderly.
The Bangladesh Red Crescent Society has mobilized 675 volunteers to support communities in the flood-affected districts. In addition to carrying out rapid assessments, teams are distributing food, clean water, hygiene kits and tarpaulins to families whose homes were destroyed or damaged by the landslides.
Md Feroz Salah Uddin, secretary general of the Bangladesh Red Crescent Society said: "Tens of thousands of homes have been destroyed which puts people further in the direct path of dangerous floods. We are seriously concerned about access to the affected populations. A critical priority for Bangladesh Red Crescent volunteers right now is to reach these stricken communities with relief supplies."
In response to the heavy flooding IFRC has just released 452,439 Swiss francs from its Disaster Relief Emergency Fund that will allow the Bangladesh Red Crescent Society to provide food, relief items and cash for 10,000 of the most affected families living in the worst hit districts.