North Korea has banned foreign tourists to guard against the spread of the new coronavirus that has emerged in China, a tour operator said.

The temporary closing of the North Korean border began on Wednesday, Young Pioneer Tours said in a statement and subsequent tweet.

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South Korea's Unification Ministry, which handles relations with North Korea, said it could not confirm the report.

Most foreign tourists to North Korea are Chinese or are people who travel to the North from China, its major diplomatic ally and biggest aid benefactor.

Young Pioneer Tours is based in China. In its statement, it said further details had not yet been confirmed by its North Korean partners.

"If you are currently booked on our upcoming tours to North Korea our staff will reach out to you to confirm further details," it said in the statement late on Tuesday.

confirmed that #northkorea are closing their borders https://t.co/hkVTUM9oPC — Young Pioneer Tours (@YPioneerTours) January 21, 2020

Tourism has been one of the few legitimate sources of foreign currency for North Korea, which is under multiple rounds of United Nations sanctions over its nuclear programme. The North has been building ski slopes, spas and other attractions to entice more tourists and boost its economy.

North Korea has not reported any cases of the new virus, which originated in Wuhan and has now infected at least 440 people around the country. Its state media has reported about the outbreak in China to try and increase public awareness of the disease and symptoms.

In 2003, North Korea closed its borders during the scare over severe acute respiratory syndrome (SARS), which was caused by a different coronavirus. At the time, North Korea suspended South Korean tours to its scenic mountain for two months, South Korean Unification Ministry spokesman Lee Sang-min said. The joint tour programme was eventually suspended in 2008 after a North Korean soldier shot and killed a South Korean tourist.