Heavy monsoon rains in Nepal, Bangladesh have killed more than 160 people in the last week, officials said on Tuesday, as authorities rushed to rescue those missing or stranded in flooded areas.
Deadly flooding in parts of India, Nepal and Bangladesh has killed at least 245 people in the past few days.
Survivors are urgently calling for rescue boats, food and other forms of help.
With hundreds of thousands of people affected by the floods, the government was focusing on moving in relief supplies as soon as possible, said Ram Krishna Subedi, a home ministry spokesman. Nepal's government has been under criticism for not being able to reach people desperate for help. Four districts located along the Indian-Nepal border in Bihar Kishanganj, Araria, Purnea and Katihar districts are under high inundation affecting almost one million people.
Some 200,000 people were temporarily living in the more than 250 relief camps that the government has set up in school and government buildings.
In the northern Indian state of Bihar, floods have killed 56 people since Sunday and affected more than 6 million, said Anirudh Kumar, additional secretary in the state Disaster Management Department. India saw around 110 death in its northern states, and Bangladesh is reporting 27 dead so far, with major rivers flowing at dangerously high levels.
Hundreds have died in torrential rain, floods and landslides in during the monsoon, which hits the country's southern tip in early June and sweeps across the nation, lasting into September.