People gather on a road as traffic is affected by a landslide caused by an earthquake, in Kurintar, Nepal April 27, 2015. [Photo/Agencies]

KATHMANDU - The death toll from Saturday's earthquake in Nepal has climbed to 4,264 people, including 20 mountaineers, and more than 7,000 others were injured, said the National Emergency Operation Center of Nepal's Home Ministry on Tuesday morning.

More than 400,000 houses were destroyed or damaged by Saturday' s earthquake, which was followed by a series of aftershocks, including a 6.7-magnitude quake on Sunday afternoon, affecting more than 6.6 million people, according to the emergency operation center.

Shock turned to anger in Nepal on the day as some of the tens of thousands of people stricken by the weekend's devastating earthquake expressed frustration at what they said was their government's slow response to the crisis.

International aid has finally begun arriving in the Himalayan nation of 28 million people after the major quake that struck at about midday on Saturday. A Home Ministry official in the capital, Kathmandu, said the death toll from the 7.9 magnitude quake stood at 4,010, with 7,598 injured.

Nepal's most deadly quake in 81 years triggered a huge avalanche on Mount Qomolangma that killed at least 17 climbers and guides, including foreigners, the worst single disaster on the world's highest peak.

A series of aftershocks, severe damage from the quake, creaking infrastructure and a lack of funds have slowed the disbursement of aid to those most in need.

The head of neighbouring India's National Disaster Response Force (NDRF), one of the first foreign organisations to arrive in Nepal to help in the search and rescue effort, said finding survivors and the bodies of the dead would take time.

NDRF Director General O.P. Singh said heavy equipment could not fit through many of the narrow streets of Kathmandu, Nepal's capital.

"You have to remove all this rubble, so that will take a lot of time ... I think it's going to take weeks," he told Indian television channel NDTV late on Monday.

For a third night, many people across the country slept in the open, their homes either flattened or threatened by tremors that spread more fear among a traumatised population.

In Kathmandu, as elsewhere, thousands are sleeping on pavements, roads and in parks, many under makeshift tents.