Fears are mounting that people forced from their homes by floods that have hit south Asia could be exposed to deadly epidemics as emergency teams struggle to deal with almost 20 million in need of help. As the death toll from the most recent monsoon floods reached 330 - most of them in central India and Bangladesh - experts said immediate action was needed to prevent outbreaks of measles, gastroenteritis, dengue fever and other diseases.
Marzio Babille, Unicef's health chief in India, said that if action was not taken there would be "many deaths". "The scale is massive. The challenge is enormous for the government and those who are helping," he said.
In the northern state of Assam, Chief Minister Tarun Gogoi said: "We are really worried about the outbreak of an epidemic in Assam now."
Two weeks of persistent rain have brought the worst floods in living memory to parts of southern Asia. Though monsoon rains provide vital irrigation and replenish water supplies, hundreds of people are killed every year as a result of the flooding and inadequate preparation by the authorities. Officials say more than 1,100 people have died so far this year, not including the most recent casualties.
In the impoverished Indian state of Bihar, four military helicopters were being used to drop food, clothing and medicine but officials said 20 such helicopters were required. In Bihar alone, almost 10 million people have been affected by the flooding and more than 80 have died.
"Each pilot is carrying out 12 sorties a day and they have reported huge devastation in central and north Bihar," said Ramesh Kumar Das, a spokesman for India's Defence Ministry.
One man contacted by television in Bihar said he had been struggling to feed his children. "I have been dividing one small piece of bread among four of my children, and I have been starving and somehow surviving," Siraj Ahmed said.
Meanwhile, in neighboring Bangladesh, officials said at least 120 people have now been confirmed dead. Another 37 people were officially missing. Many of the dead have been killed as a result of fatal snake bite.
Around 40 of the country's 64 districts have been affected and around 300,000 people have been moved into emergency relief camps. Others have taken shelter on raised roads and railway embankments, taking with them their cows, buffaloes and goats.
Officials said that while the floods were receding in the north, the situation could get worse in the centre of the country and in the capital, Dhaka.
Fakhruddin Ahmed, the head of Bangladesh's military-backed government, visited the north-western district of Sirajganj. Despite the extent of the devastation, the government had sufficient food and medicine, he said, and foreign assistance was not required. "All of us, irrespective of [political] party, opinion, profession or religion, should come forward and unite behind coordinated efforts to tackle this grave situation," he said.
Despite his call for unity, many opposition politicians have refused to co-operate with the military's efforts. They have claimed that despite the government's insistence that it was managing the situation, the reality is very different.