The Himalaya region was hit by a powerful earthquake, leaving 53 people confirmed dead in India, Nepal and Tibet.

However, rain and landslides have hampered the search for any survivors after the 6.9 magnitude quake, which hit the isolated Himalayan region of Sikkim on Sunday, at 6.11pm local time.

The epicenter was located 68 km northwest of Sikkim's capital Gangtok, at a depth of 19.7 km.

Police on Monday confirmed  31 casualties in the "Shangri-la" northeastern Indian state of Sikkim.

Army officers and border police stationed in the north of Sikkim, which has a large military deployment close to the Chinese border, worked through the night to rescue at least 200 villagers caught under fallen debris. However, further rescue efforts have been hampered due to thick cloud preventing helicopters from flying over the affected areas.

However, they may not reach many areas until Tuesday because high mountain passes are blocked.

"The situation doesn't look good," an official from the U.N's disaster management team in New Delhi told Reuters. "My feeling is the death toll and number of injured are going to increase."

"People are still panicky," Pawan Thapa, a resident of Gangtok, capital of Sikkim, told Reuters by phone. "We spent the whole night outside our homes."

It has been raining for four straight days in parts of Sikkim and the temperature in the quake zone was about 8 degrees Celsius (46 degrees Fahrenheit).

Sikkim, which borders Bhtan, Tibet and Nepal, is a rarely-visited Buddhist kingdom known for its spectacular mountains and lakes. It is India’s least-populated state, occupied by 500,000 residents.

"Even if the number of casualties is low, there is likely to be a huge need for humanitarian assistance for affected civilians whose homes have been destroyed and who need food and shelter. The U.N. is taking this very seriously," said the U.N. official, who asked not to be named.

Several thousand people fled their damaged homes to government shelters in Gangtok. More than 100 people were injured, while hundreds of tourists, mainly Indian, were stranded on the main road out of the state to West Bengal in the south.

Outside India, at least seven people died in Nepal, three of them killed when a wall on the perimeter of the British Embassy in Kathmandu collapsed on to a car and a motorcycle. Seven were also reported dead in Tibet, China's state-run news agency Xinhua said.

The quake was felt all the way to New Delhi in India as well as to Bangladesh, shaking buildings. At least 10 people were injured and some buildings suffered minor damage.