Pyongyang has reportedly told embassies to consider evacuating their employees in the case of a war. If they do not, North Korea cannot guarantee foreign diplomats' safety, it was said.
North Korea issued the warning to embassies in its capital Pyongyang on Friday, according to reports from the British Foreign Office, as well as Russian and Chinese media.
The foreign missions would have until April 10 to notify North Korea authorities of any evacuations, after which date Pyongyang could no longer guarantee their safety.
British diplomats said the warning appeared to be worded as a question rather than a command.
"Our understanding is that the North Koreans were asking whether embassies are intending to leave, rather than advising them to leave," a Foreign Office spokeswoman said on condition of anonymity.
In a statement, British officials expressed skepticism at the seriousness of North Korea's advisory warning.
"We believe they have taken this step as part of their continuing rhetoric that the US poses a threat to them," the British Foreign Office statement said, according to the news agency Associated Press.
The UK reaction followed reports in the Russian and Chinese media that their governments had also been contacted with a similar proposal.
Russia's foreign minister told reporters that Pyongyang must explain itself.
"We are very perturbed about the supercharged tensions, which for now are verbal. We want to understand the causes of this proposal," Foreign Minister Sergey Lavrov was reported as saying by Russia's RIA-Novosti news agency.
The advisory came amid heated rhetoric emanating from Pyongyang. Since late last week, North Korean leader Kim Jong Un has threatened the US and South Korea more than once with a missile strike or nuclear attack. In response, Washington has deployed aerial defense to South Korea and to its Pacific island territory Guam.
North Korea threats 'alarming'
Kim Jong Un's threats have alarmed the international community, despite their familiar tone. Since issuing a war threat late last week, Pyongyang has barred South Koreans from travelling to an industrial zone complex within North Korean territory that employs workers from both sides of the border.
It has also moved a medium-range missile to its east coast.
UN Secretary-General Ban Ki-moon has admonished Pyongyang for crying nuclear war:
"Nuclear threat is not a game," Ban said while in Madrid on Thursday. "It's very serious and I think they have gone too far in the rhetoric. I am concerned that, if by any misjudgment, by any miscalculation of the situation, a crisis happens in the Korean Peninsula, this really would have very serious implications."
US amps up defense
The US has said it is "taking all the necessary precautions" following repeated threats of an attack from North Korea.
This week, the Pentagon announced it would send a defense system to Guam to shoot down incoming missiles and warheads.
"The United States remains vigilant in the face of North Korean provocations and stands ready to defend US territory, our allies, and our national interests," the Pentagon's statement read.
Guam lies about 2,000 miles (3,218 kilometers) southeast of North Korea.
Guam Governor Eddie Bazo Calvo said that his administration is providing information to help residents prepare in case of an attack, including guidance for where to hide if radiation is in the air. Calvo said, however, that an attack was unlikely and he has advised the public to go on with their daily lives.
kms/rc (AP, AFP, Reuters)