Nepali families held symbolic funerals on Wednesday to "liberate the souls" of relatives missing since deadly flash floods swept away their villages and homes in the Himalayan region a week ago.

Emergency teams have recovered more than 1,100 bodies, and nearly 4,500 people are missing after the gigantic wave of freezing water, rocks and debris triggered by a high-altitude glacial collapse roared down the China-Nepal border on 26 August.

After days of searching shelters and mortuaries, relatives of some of the missing lost hope and began conducting last rites, burning straw effigies in Hindu rituals.

"We had to do this to set his soul free, so that he is at peace and happy wherever he is," said Dolma Newar Tamang, flanked by her sobbing son, at a funeral for her husband.

He had been en route to China when the disaster struck.

"I saw the news and called him," she told AFP. "I called repeatedly, but he never picked up."

A week on from the colossal disaster, Nepali rescuers are still seeking survivors, including by digging through packed sludge that has entombed multiple tunnels of hydropower plants.

So far, rescuers have recovered only bodies from tunnels, but teams were still digging, drilling and blasting through debris.

Nepal's Foreign Minister Shisir Khanal said he still hoped some missing could be alive.

"Miracles do happen," he told AFP. "At this point, I do not want to completely give up hope."

‘Global responsibility’

There is growing anger at the scale of destruction to hit Nepal, a largely rural nation of 30 million people.

The country has contributed little to the greenhouse gas emissions driving global warming, but is among those suffering its consequences.

Nepal's Prime Minister Balendra Shah warned the catastrophe was "a serious indication" of the risks the Himalayan nation faces.

Scientists say the Himalayas, the world's highest mountain range, are warming rapidly as global temperatures rise, accelerating glacier melt.

Glaciers in the wider Himalayan and Hindu Kush ranges are a crucial water source for around 240 million people in the mountainous regions, as well as for another 1.65 billion people in the South Asian and Southeast Asian river valleys below.

"Climate change is a global contribution, and disaster response is also a global responsibility," Shah said in a social media post.

Kathmandu has warned reconstruction could cost billions of dollars.

Nepal, which marks a year this month since deadly mass protests over rampant corruption and a woeful economy overthrew the then government, has limited resources to respond to a disaster of this scale.

In an illustration of the scale of destruction, Chinese state media said road access to hard-hit Gyirong Port in Tibet had finally been restored on Wednesday after "days of round-the-clock repair work".