GORKHA, Nepal (AFP) - Hungry and desperate villagers rushed towards relief helicopters in remote areas of Nepal Tuesday, begging to be airlifted to safety, four days after a monster earthquake killed nearly 4,500 people.

"The ground keeps shaking, even this morning it did. Every time it feels like we will be swallowed, that we will die now. I want to get out of here!" said Sita Gurung.

As the Himalayan nation's Prime Minister Sushil Koirala said getting help to remote areas was a "major challenge", aid finally began reaching areas which had to fend for themselves since Saturday's 7.8-magnitude quake.

The official toll in Nepal alone stood at 4,356 while more than 100 people died in neighbouring countries such as India and China.

Around 8,000 people had been injured while the United Nations estimated that eight million people had been affected.

Among the dead were 18 climbers who were at Mount Everest base camp when an avalanche triggered by the quake flattened everything in its path. The victims included two American climbers, an Australian and a Chinese.

Countries far and wide have joined the relief effort in what is one of Asia's poorest countries, with neighbouring India playing a leading role.

In Gorkha, one of the worst-hit districts, terrified residents ran with outstretched arms towards an Indian army helicopter, pleading for food and water.

An AFP journalist on board saw scores of houses across several villages in the district turned into twisted mounds of wood and corrugated tin roofs.

"We haven't had any food here since the earthquake. Everything has changed, we don't have anything left here," 24-year-old Sita Gurung told AFP, gesturing towards her ruined home in the village of Lapu.

An army officer lifted her onto a stretcher and carried her away.

Military planes from numerous countries such as the United States, China and even Israel have joined the rescue effort.

Koirala told an emergency all-party meeting the government was sending desperately needed tents, water and food supplies to those in need.

But he said authorities were overwhelmed by appeals for help from remote Himalayan villages.

"Appeals for rescues are coming in from everywhere," a statement from Koirala's office quoted him as saying.

"But we have been unable to initiate rescue efforts in many areas at the same time due to lack of equipment and rescue experts." "The situation here is not good. So many have lost their homes. They don't have enough water or food," said Udav Prasad Timilsina, the head official in Gorkha.

"We haven't even been able to treat the injured. We are in urgent need of essentials like food, water... and medicines and tents. Rescuers are coming in but we need help." With fears rising of food and water shortages, Nepalis were rushing to stores and petrol stations to stock up on essential supplies in the capital Kathmandu.

Nepal has declared a state of emergency after the disaster, its deadliest in more than 80 years.

Another 73 people died in India. The toll in China's far western region of Tibet, which neighbours Nepal, rose to 25, the official Xinhua news agency said.

- Families flee Kathmandu -

Families who work in Kathmandu were packing onto buses - some even sitting on the roofs - in an exodus from the city.

Those who remained in the capital were sleeping outdoors in tents in parks and other open spaces. Many had lost their houses, others were too terrified to return home after several powerful aftershocks.

With just plastic sheets to protect them from the elements, many were desperate for aid and information on what to do next.

"We've been staying here for three days, living under canvas. We're counting every bite we eat, every drop we drink," said 28-year-old housewife Rama Shrestha, who is camping out with her five-year-old son.

"And now on top of everything, it is raining. What can we do? Where can we go? We are too scared to return home, what if another one strikes?"

Hospitals have been overwhelmed, with morgues overflowing and medics working flat out to cope with an endless stream of victims suffering trauma or multiple fractures.

Pledging US$10 million (S$13.24 million) in relief to help the victims, US Secretary of State John Kerry said he had been shocked by the "gut-wrenching" images of the death and destruction.

Australia said Tuesday it was raising its aid to US$4.7 million and sending a military plane to bring in relief supplies and evacuate stranded citizens.

But lack of space at the only international airport was hampering efforts to bring in relief by air.

Japan's International Cooperation Agency said a disaster relief team was making a third attempt Tuesday to enter Kathmandu, after being twice turned away from a crowded airport on Monday.

The quake is a serious blow to the economy of one of the world's poorest countries, already reeling from a decade-long civil war that ended in 2006.

Nepal and the rest of the Himalayas, where the Indian and Eurasia tectonic plates collide, are particularly prone to earthquakes.

A 6.8 magnitude quake hit eastern Nepal in August 1988 killing 721 people, and a magnitude 8.1 quake killed 10,700 people in Nepal and India in 1934.