All six people aboard a tourist helicopter in Nepal were killed when it crashed soon after take-off in the Everest region on Tuesday, aviation authorities said.

The Manang Air flight was heading for the capital Kathmandu from near Lukla, the gateway for climbing expeditions to the world's highest peak, with five Mexican travellers and a Nepali pilot onboard.

The chopper lost contact about 10 minutes after taking off at 10:04 am (0419 GMT).

"Six bodies have been found at the crash site," Gyanendra Bhul of the Civil Aviation Authority of Nepal told AFP.

Two helicopters and teams on the ground had been deployed for search and rescue.

"Weather did not allow the helicopters to land close to the area. Teams on foot are heading there to retrieve the bodies," Bhul said.

Local search-and-rescue officials at the crash site could not be reached for comment.

Prime Minister Pushpa Kamal Dahal had "expressed grief" over the incident, his office said on Twitter.

Nepal has a booming private helicopter industry, flying tourists and goods to remote corners of the Himalayan nation where road access is limited or non-existent.

But the country is notorious for its poor air safety, and Tuesday's incident is the latest in a string of aviation accidents in the country.

One person was killed and four were injured in May when a helicopter crashed in eastern Nepal after dropping off goods for a hydroelectricity project.

The Himalayan republic has some of the world's most remote and tricky runways, flanked by snow-capped peaks with approaches that pose a challenge even for accomplished pilots.

The weather can also change quickly in the mountains, creating treacherous flying conditions.

Nepal's aviation sector has also been plagued by insufficient training and maintenance.

A plane crash in the country's west killed all 72 people on board in January.

The Yeti Airlines flight had plummeted into a steep gorge, smashed into pieces and burst into flames as it approached the central city of Pokhara.

In 2018, a US-Bangla Airlines plane crash-landed near Kathmandu's notoriously difficult international airport, killing 51 people and seriously injuring 20.

In 1992, in Nepal's deadliest air accident, all 167 people aboard a Pakistan International Airlines plane died when it crashed on approach to Kathmandu airport.

Just two months earlier a Thai Airways aircraft had crashed near the same airport, killing 113 people.

The European Union has banned all Nepali carriers from its airspace over safety concerns.