Foreign diplomats in Pyongyang huddled on Saturday to discuss a North Korean evacuation advisory as concerns grew that the isolated state was preparing a missile launch at a time of soaring nuclear tensions.

The heads of all EU missions had agreed to meet to hammer out a common position after Pyongyang warned embassies it would be unable to guarantee their safety if a conflict broke out and that they should consider leaving.

The U.S. military is set to deploy an unmanned spy plane in Japan to boost surveillance capabilities as North Korea apparently readied for missile launches, a newspaper report said on Saturday.

The Global Hawk will be stationed at the U.S. airbase in Misawa, northern Japan, in the first ever deployment of the aircraft in the country, the Sankei Shimbun reported, quoting government sources.

North Korea refused on Saturday to lift a ban on South Koreans accessing their companies in a joint industrial zone on the North side of the border.

Entry to the Seoul-funded Kaesong complex has been barred since Wednesday, as inter-Korean tensions have risen to their highest level for years.

North Korea has no choice but to "confront" the United States which is to blame for tensions in the Korean peninsula, a top Iranian commander said in remarks carried on Friday by Fars news agency.

"Tensions in the region are due to excessive demands by the United States... and its tightening of the noose on North Korea," said armed forces deputy chief Brigadier General Masoud Jazayeri.

A powerful 6.2 magnitude earthquake struck early Saturday in eastern Russia near the border with China and North Korea, the U.S. Geological Survey said.

The epicenter of the quake, which struck at 1300 GMT Friday, was southwest of Vladivostok, around nine kilometers (five miles) from the Russian border town of Zarubino, at a depth of 561 kilometers (350 miles), the USGS said.

North Korea has suggested to Russia that it should consider evacuating its embassy in Pyongyang due to the upsurge of tensions on the Korean peninsula, a Russian diplomat said Friday.

"A representative of the North Korean foreign ministry suggested that the Russian side examine the question of evacuating the employees of the Russian embassy," embassy spokesman Denis Samsonov told Russian news agencies.

North Korea has now moved two intermediate range missiles to its east coast and loaded them on mobile launchers, South Korea's Yonhap news agency said Friday, citing a top government official.

The Defense Ministry, which had confirmed the movement of one missile the day before, declined to comment on the new report.

The South-North Korean industrial complex that has become a chip in a high-stakes game of military brinkmanship on the Korean peninsula was closed Friday for a scheduled holiday, officials said.

The 53,000 North Koreans who work at the 123 South Korean companies in the Kaesong joint industrial zone, 10 kilometers (six miles) inside the North, took the day off, the South's Unification Ministry spokeswoman said.

The United States said it was taking "all necessary precautions" after North Korea rang fresh alarms in an escalating crisis by moving a medium-range missile Thursday to its east coast.

Seoul's defense minister Kim Kwan-Jin said the missile could reach a "considerable distance" but not the U.S. mainland, telling lawmakers it "could be aimed at test-firing or military drills".

Prime Minister David Cameron on Thursday warned that Britain would be left defenseless against the "highly unpredictable and aggressive" North Korean regime if it wound down its Trident nuclear deterrent program.

Writing in the Daily Telegraph newspaper, Cameron said the recent actions of North Korea coupled with concerns over Iran's nuclear program meant it would be "foolish" to scrap the fleet of nuclear missile submarines.