A woman carries her belongings as she walks over collapsed house after earthquake in Bhaktapur, Nepal April 27, 2015.[Photo/Agencies]

The situation is worse in remote rural areas. Highways have been blocked by landslides, and many villages and communities are without water and electricity, villagers surviving on salvaged food and with no outside help.

While aid has begun arriving in the capital, including food, medical supplies, tents and dogs trained for rescue efforts, the authorities are struggling to deliver relief further afield.

A crush at the main international airport, where relief material and rescue teams are flying in while thousands of residents are trying to leave, has slowed the flow of aid.

India and China were among the first contributors to an international effort to support Nepal's stretched resources.

On Monday, the United States announced an additional $9 million in aid for Nepal, bringing total US disaster funding to $10 million.

US and Australian military transport planes carrying search-and-rescue personnel and supplies were headed to Nepal.