"We had a very successful summit in Hanoi... this is the right chance, the golden chance for us to generate a tourist market of Vietnam to DPRK," Ham Jin of the official Korea International Travel Company (KITC) told AFP Thursday.

His company hosted a booth at a tourism fair in Hanoi this week -- with brochures advertising a dolphinarium, a science and technology complex and the Victorious Fatherland Liberation War Museum in "ever-changing" Pyongyang -- while others urged skiers to pay a visit to the Masikryong mountain resort.

Kim paid an official visit to Hanoi after his meeting with Trump, piquing curiosity among some Vietnamese eager to know more about the reclusive leader and his country.

"I want to discover this mysterious country because there are many things to see," said Do Thi Phuong Thuy, who signed up for a tour after Kim's trip.

North Korea receives an estimated 100,000 foreign tourists a year, according to industry insiders, though Pyongyang does not publish visitor data.

Ham put the number at double that and said visitor numbers grew by as much as 50 percent last year, though his figures could not be verified.

"We (use) tourism to contribute to economic development," he told AFP.

A Vietnamese tour operator at the fair said his client numbers have surged this year, but that some travellers remain wary.

"People are concerned North Korea isn't safe or is closed to the world...

there are the difficulties for us when we promote tours to North Korea," Nguyen Cong Hoan, director of Hanoi Red Tours, told AFP.

The United States has banned Americans from travelling to North Korea after the death of student Otto Warmbier, who was jailed after allegedly stealing a poster from a hotel.

He was released in a vegetative state and later died on US soil.

Once-popular tours from South Korea to Mount Kumgang near the border came to an abrupt end in 2008 when a North Korean soldier shot dead a tourist from the South who strayed off the approved path.

Trump has heralded North Korea's economic potential, praising its "great beaches" that he said would make ideal locations for condos.

North Korea is currently building a sprawling seaside resort known as the Wonsan-Kalma Coastal Tourist Area in a zone that has previously been used for artillery drills and ballistic missile launches. (AFP)