The Nepali and Chinese sides of the Everest region were closed to tourism on Wednesday due to heavy snow brought by cyclone winds, with deep snowdrifts causing a helicopter to crash as it tried to rescue stranded trekkers, authorities said.

Visited by thousands of trekkers and climbers, the region around Mount Everest has been blanketed by snow since Monday as a cyclone from the Bay of Bengal churned across India, ushering in a second bout of severe snowfall in the Himalayas this month.

Authorities in Nepal have halted trekking on many hiking routes due to rain at lower elevations and heavy snowfall on higher trails, and have urged hikers not to venture out or proceed with their treks in the Annapurna, Manaslu and Dhaulagiri areas, home to some of the world's highest peaks.

A small private helicopter flying to Lobuche near the Everest Base Camp to rescue stranded trekkers crashed when it tried to land, Civil Aviation Authority of Nepal spokesperson Gyanendra Bhul said.

CAAN video showed the helicopter, which slipped on the snow while landing, lying on its side. The pilot survived and was later rescued. It was unclear whether the trekkers had been rescued.

Stranded trekkers

Army and police rescuers guided hundreds of trekkers in Manang district to safety since Tuesday, Nepal Army spokesperson Raja Ram Basnet said.

He said about 1,500 hikers, including 200 foreigners of different nationalities, their guides and local trekkers had lost their way as hiking trails were buried under deep snow.

"Rescuers cleared the snow from trail and brought them down to safer places," Basnet told Reuters in Kathmandu.

Weather officials have forecast heavy rain and snow on Thursday and Friday due to the passage of Cyclone Montha, which roared into India's southeastern state of Andhra Pradesh on Tuesday night.

On the Tibetan side of Everest, ticket sales had been suspended since Tuesday afternoon as roads turned icy and visibility plunged, creating impassable conditions for vehicular traffic, according to the tourism department of Tingri county.

It was unclear if there were tourists trapped inside the Everest region in Tibet. The press office of the Tibetan government did not immediately respond to a Reuters request for comment.

Weather forecast data shows temperatures in Tingri are expected to dip further below freezing this week.

In early October, a blizzard stranded hundreds of trekkers near the eastern face of Everest on the Tibetan side. All of the trekkers were taken to safety in a large-scale rescue operation that spanned several days under sub-freezing conditions.

In Nepal, more than 50 people had died due to floods and landslides triggered by heavy rains.