The US government will ban Americans from travelling to North Korea due to "the serious risk of arrest" after a US student was jailed while on a tour and later died, the State Department says.
US Secretary of State Rex Tillerson authorised a 'Geographical Travel Restriction' on all Americans' use of a passport to the country, spokeswoman Heather Nauert said on Friday.
"Once in effect, US passports will be invalid for travel to, through and in North Korea, and individuals will be required to obtain a passport with a special validation in order to travel to or within North Korea," Nauert said.
The move was due to "mounting concerns over the serious risk of arrest and long-term detention under North Korea's system of law enforcement", she added.
The State Department plans to publish a notice in the Federal Register next week, starting a 30-day clock before the restriction takes effect, Nauert said.
Koryo Tours, which offers tours to North Korea, had said the ban would be announced this month. The Swedish embassy in Pyongyang, which handles consular affairs for the United States in the North, informed Koryo of the ban, but did not say how long it would last, the company said.
"But it does seem to be the case that in just over a month, it will be impossible for Americans to visit as tourists," Koryo Tours general manager Simon Cockrell told Reuters by telephone.
Ms Nauert said Americans who want to travel to North Korea "for certain limited humanitarian or other purposes" can apply for a special passport to do so.
Young Pioneer, another company that arranges tours to North Korea, took US student Otto Warmbier to the country at the end of 2015.
He was arrested there and sentenced to 15 years of hard labour for an incident at his hotel where he was accused of trying to steal a propaganda banner.
North Korea released the 22-year-old Mr Warmbier in June in a coma and he died days after getting back to the United States. The circumstances surrounding his death are not clear, including why he fell into a coma.
North Korea has said through its state media that Mr Warmbier's death was "a mystery" and dismissed accusations that he had died as a result of torture and beating in captivity.
The isolated North Korea allows foreign tourists to visit but their travel is strictly limited.