Hong Kong, China: International aid groups and governments escalated efforts to dispatch rescuers and supplies to earthquake-hit Nepal on Sunday, but severed communications and landslides in the Himalayan nation posed formidable challenges to the relief effort.

As the death toll passed 1,800, the US together with several European and Asian nations sent emergency crews to reinforce those scrambling to find survivors in the devastated capital, Kathmandu, and rural areas cut off by blocked roads and patchy phone networks.

‘Roads have been damaged or blocked by landslides and communication lines are down, preventing us from reaching local Red Cross branches to get accurate information,’ said Jagan Chapagain, Asia Pacific director of the International Federation of the Red Cross and Red Crescent Societies (IFRC).

The IFRC said it was extremely concerned about the fate of rural villages close to the epicentre of the quake, some 80 kilometres (50 miles) from Kathmandu.

‘We anticipate that there will be considerable destruction and loss of life,’ Chapaign added.

Other aid organisations responding to the emergency also struggled to assess requirements across the nation, and spoke of the fearsome effects of the quake.

‘We witnessed terrible scenes of destruction -- hospitals were evacuated with patients being treated on the ground outside, homes and buildings demolished and some roads cracked wide open,’ said Eleanor Trinchera, Caritas Australia Program Coordinator for Nepal.

Survivors slept in the open in Kathmandu overnight, braving the cold for fear of being crushed by the teetering ruins of buildings.

Hundreds of structures, including office blocks and a landmark nine-storey tower, crashed to the ground at around midday on Saturday when the 7.8-magnitude quake struck.

Meanwhile snowfalls on Saturday thwarted efforts to airlift survivors from an avalanche that hit part of Everest base camp, killing at least 17 people, although choppers started landing on Sunday.

'Heartfelt sympathies'

Secretary of State John Kerry said the United States was working closely with the Nepal government to provide assistance.

‘To the people in Nepal and the region affected by this tragedy we send our heartfelt sympathies,’ he said.

A US disaster response team was en route to Nepal and an initial $1 million in aid to address immediate needs had been authorised, the US Agency for International Development said.

Neighbouring India dispatched two military transport planes to help with the rescue and relief efforts as it emerged that at least 47 people had died there from the effects of the massive quake.

There were similar offers from around the region, including Sri Lanka, Pakistan and, further afield, Japan.

China said it had dispatched a 62-member search and rescue team with sniffer dogs and had started work on an emergency humanitarian aid plan, state news agency Xinhua reported.

Chinese state media said 17 people had also been killed by the earthquake in Tibet.

Singapore's government said its Civil Defense Force was to send a 55-man search-and-rescue team while members of country's armed forces would also support the relief efforts with deployment of ‘suitable resources’.

The European Union said its humanitarian experts were heading to the crisis areas.

‘The full extent of the casualties and damage is still unknown but reports indicate they will likely be high, both in terms of loss of life, injuries and damage to cultural heritage,’ an EU statement said.

Others considering what help they could provide included Malaysia, New Zealand and South Korea.

'Urgent need' for assistance

Germany, Britain and Spain also pledged support and assistance, with Norway promising to provide 30 million krone ($3.9 million, 3.5 million euros) in humanitarian aid.

British Prime Minister David Cameron said the earthquake was ‘shocking news’ and vowed his country, which swiftly sent a team of humanitarian experts to Nepal, ‘will do all we can to help those caught up in it’.

Israel also said it was sending an aid delegation to Nepal, including a team of paramedics and doctors.

Charity Christian Aid launched an appeal for funds and said it was working with partner agencies to reach the worst hit areas.

‘It's clear from what has emerged so far that there is an urgent need for emergency shelters, food and clean drinking water, warm clothing blankets and hygiene kits,’ said the group's regional emergency manager Ram Kishan in a statement.