Rain and landslides have hampered the search for survivors of a 6.8 magnitude earthquake that killed at least 62 people in northeastern India, Nepal and Tibet.
Thick clouds kept helicopters from flying over the affected areas, authorities told the AFP news agency on Monday. They said the number of casualties could rise as rescue teams had not been able to reach remote areas.
At least 18 people were confirmed dead in the Indian state of Sikkim, the epicentre of Sunday night's quake. More deaths were reported in neighbouring Nepal and Tibet.
"The situation doesn't look good," an official from a UN disaster management team in the Indian capital, New Delhi, told the Reuters news agency.
Sikkim, India's most sparsely populated state located in the Himalayas surrounded by Nepal, Bhutan and Tibet, is prone to landslides.
The quake also left several dead in both Nepal and Tibet.
Deadly quake rattle India and Nepal
Landslides and heavy rain were slowing the arrival by road of at least 400 rescue workers and doctors trying to reach the worst affected area after landing at the nearest airport almost 100 km away from the epicentre.
Army officers and border police stationed near the epicentre, which has a large military deployment near the Chinese border, rescued at least 200 villagers.
Many towns in Sikkim have experienced power cuts, while thousands are being sheltered by the government.
At least 100 people were injured in Sikkim alone, while hundreds of tourists, mainly Indian, were stranded on the main road out of the state to West Bengal in the south.
The quake was also felt as far as New Delhi, with residents also rushing out of shaking buildings on Sunday.
In Tibet's Yadong County, just 40km from Sikkim, the earthquake caused hundreds of landslides disrupting traffic, telecommunications, power and water supplies.
In Kathmandu, the capital of Nepal 270km from the west of the quake's epicentre, buildings were evacuated and traffic came to a standstill.
Three people died when a wall of the British Embassy collapsed. Those dead included a motorcyclist and his eight-year-old child who were struck as they rode past, police said.
Two others died in Dharan in Sunsari district, including a five-year-old child, llegislators in parliament hurried out of the building shouting when the quake struck in the middle of a debate on the budget, witnesses said.