Hoping to open up a side of North Korea rarely seen by outsiders, a New Zealander with extensive climbing experience in North and South Korea is leading the first group of foreign tourists - two Australian women and two Norwegian men - to be allowed to go off road and camp under the stars on Mount Paektu, a huge volcano that straddles the border that separates China and North Korea.

In 946 AD Paektu was the site of one of the largest eruptions in history. It is considered one of the most beautiful natural sites in North Korea and is still active, though there haven't been any big eruptions in recent years.

It's revered in the North for its links to the ruling Kim family and is considered the spiritual home of the Korean revolution. Trips to the mountain are popular with North Koreans and also with Chinese tourists and small foreign tour groups that stay in nearby hotels and drive to its crater to see the blue waters of Lake Chon in Paektu's caldera.

But Roger Shepherd, founder of Hike Korea, which is based in the South, managed to convince North Korean government officials to let him take his guests off the beaten path.

Several reconstructed "secret campsites", said to have been used by guerillas to fight Japanese colonial rulers before 1945, dot the mountain.

On Saturday, the group climbed the mountain from near its base, walked to the lake from the rim and then hiked out across a volcanic plateau to pitch their tents for the first of five nights they were to spend on the hike.

North Korea under leader Kim Jong-un has placed a high priority on tourism to boost much-needed foreign currency.

Massive infrastructure projects are underway in several locations, including at Samjiyon, the largest city near Mount Paektu, and in the eastern port city of Wonsan and the adjacent Mount Kumgang area, which was open to South Korean tourists until around 2008, when a South Korean woman was shot for wandering into a restricted area.

But any big increase in foreign tourist numbers will require an easing of international sanctions in place to push Kim Jong-un to abandon his nuclear weapons program.

US President Donald Trump banned Americans from visiting North Korea after the death of US student Otto Warmbier, who died shortly after his release from North Korean custody for allegedly trying to steal propaganda banner.

But Shepherd said incidents involving tourists are rare and that the trekkers had quickly bonded with their North Korean guides.

"Out here it's very apolitical. There's no need for the nonsense out here. We're all trying to do the same thing. Work together as a team, pitch tents, eat together walk together. In my experience that's a good way for these guys to see the real people of this country," he said.

Australian Associated Press