"The death toll could go up to 10,000 because information from remote villages hit by the earthquake is yet to come in," Mr Koirala said in an interview.

"The government is doing all it can for rescue and relief on a war footing," he added. "It is a challenge and a very difficult hour for Nepal."

A home ministry official put the latest death toll at 4,349. If the death toll does reach 10,000, that would be even higher than the 8,500 killed in a massive 1934 quake, the Himalayan nation's worst disaster to date.

Koirala was abroad when the 7.9 magnitude quake struck on Saturday. He returned on Sunday. He has issued orders to his government to improve coordination of the relief effort and will address the nation later on Tuesday, an aide said.

Appealing for foreign assistance, PM Koirala said Nepal needed tents and medicines. Many people are sleeping out of doors because their homes have been destroyed or may not withstand the dozens of aftershocks that have hit the country, he said.

"The government needs tents, much medicine. People are sleeping in fields and rains," he said. "There are more than 7,000 people injured. Their treatment and rehabilitation is going to be a big challenge."

International aid has finally begun arriving in the Himalayan nation of 28 million people, three days after the quake struck, but disbursement is slow.

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.

The United Nations said eight million people were affected by the quake and that 1.4 million people were in need of food.