A helicopter flying out of the Mount Everest area in Nepal with foreign tourists has gone missing.

The aircraft was carrying five foreign tourists on a sightseeing tour to the world’s highest peak and was returning to the capital, Kathmandu, on Tuesday morning.

A search effort is under way involving another helicopter in the sky and police and soldiers on the ground. Much of the mountainous area is only accessible on foot with no roads.

Airport official Sagar Kadel said weather conditions had caused changes to be made to the helicopter’s flight route.

It is common for flights to be delayed and routes changed during the monsoon season amid heavy rains.

The tourist and mountaineering season ended in May with the onset of the rainy season and tourist flights to the mountains are not common at this time of year as visibility gets poor and weather conditions become unpredictable.