A Christian celebration has turned to tragedy in the Highlands of Papua New Guinea after some 30 people — including children — got lost in the mountainous terrain 10 days ago with limited food and no shelter.

Key points: Rescue pilots say they can only take three people at a time

Rescue pilots say they can only take three people at a time The group are at an elevation of 10,000 feet with temperatures as low as 8 degrees

The group are at an elevation of 10,000 feet with temperatures as low as 8 degrees They were traveling to mark 100 years since German missionaries came to the area

Rescue workers were notified about the situation after some of the travellers made it down from the mountain over the weekend and reported that dozens were still trapped.

A helicopter rescue mission has been underway since Sunday, but the incident has already claimed the lives of at least eleven of the travellers, including a local pastor, whose body was recovered on Sunday.

Three others remain unaccounted for in the area.

The group set off 10 days ago, attempting to reach a religious celebration in the town of Kabwum, but became lost in the Saruwaged Ranges of Morobe Province.

'We can only lift three people at a time'

Map Map showing the town of Kabwum near the Saruwaged Ranges in PNG's Highlands

Helicopter pilot Jurgen Ruh said his team managed to rescue eight people on Sunday, adding that he was to be back in the air again on Monday to drop off food and try and help those still stuck on the mountain.

"We can only lift three people at a time," Mr Ruh told the ABC.

"Those mountain ranges can be cloudy for days and they're only accessible for a few hours in the morning."

He described the terrain as tough, with an elevation of up to 10,000 feet and with temperatures dropping to as low as 8 degrees overnight.

"It's cold and the weather is bad — they are not prepared for the altitude and the freezing weather," Mr Ruh said.

The group have been stuck on the mountain for 10 days. ( Supplied: Erebiri Zurenuoc/The National )

Food, warm clothing, and blankets have been delivered to those still trapped in the area — there is an appeal for more resources to be donated towards the lost group.

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The group of Christians were traveling to a celebration to mark the 100-year anniversary since the arrival of German missionaries to the area.

The Lutheran missionaries established the church there on August 10, 1919, and celebrations have been ongoing in surrounding towns for days.

PNG journalist Scott Waide said the journey usually takes two days, but the group probably took a wrong turn amid bad weather and lost their way.

Many groups had been travelling to and from the celebrations from their villages, but with few roads, the trip can mean a dangerous trek across remote and mountainous terrain.

The main day of celebrations were expected to take place on Monday with Prime Minister James Marape set to arrive in the region, but the celebrations have been marred by the situation as rescue efforts continue.

The ABC has contacted the Papua New Guinean Government for comment but they did not reply at the time of writing.