Rescuers evacuate people from flooded areas. (Photo: Reuters)

The Home Ministry said it is working to rescue people stranded on the highways. Nepal's army said 4,000 people have been rescued, and helicopters, motorboats and rafts are still bringing stranded people to safety.

The International Centre for Integrated Mountain Development (ICIMOD), a Nepal-based think tank, said the disaster was made worse by unplanned urban encroachment around the Bagmati River, which flows through the capital.

Many people affected by the floods need safe drinking water and temporary housing. The floods have blocked transport of food supplies to the capital. Traders say the supply of fresh fruits and vegetables has been drastically reduced.