Rescuers in Pakistan are struggling to reach 27,000 people stranded by severe flooding.
The worst monsoon rains in 80 years have destroyed thousands of homes and vast swathes of farmland.
At least 1,100 people have died and, with entire communities devastated, it is now estimated that more than 1.5 million people desperately need help, the BBC reports.
The United Nations, China and the United States have already pledged aid for the rescue effort.
Pakistan's military has joined the relief effort, but some survivors say the government response has been slow and inadequate.
Part of the main north-south motorway into the region was reopened on Sunday, before reportedly closing again. The brief opening allowed some aid supplies into the flooded area while also permitting people to flee.
Pakistan's army says it has committed about 30,000 troops to the relief effort, but winching individuals to safety is a slow process.
Aid agencies say there is now a real danger of the spread of water-borne diseases including diarrhoea, asthma, skin allergies and cholera in some areas.