South Korea says North will pay a 'severe price' for missile launch

South Korea said on Wednesday North Korea's announced plan to launch a satellite is really a plan to launch a long-range missile and warned that the North will pay a "severe price" if it goes ahead.

North Korea should immediately call off the planned launch, which is a violation of U.N. Security Council resolutions, the South's presidential Blue House said in a statement.

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Seoul's warning came after the North notified U.N. agencies late on Tuesday of its plan to launch what it called an "earth observation satellite" some time between Feb. 8 and 25.

"North Korea's notice of the plan to launch a long-range missile, coming at a time when there is a discussion for Security Council sanctions on its fourth nuclear test, is a direct challenge to the international community," the Blue House said.

"We strongly warn that the North will pay a severe price ... if it goes ahead with the long-range missile launch plan," it said.

Japanese Prime Minister Shinzo Abe said he would work with the United States and others to "strongly demand" that North Korea refrain from what he described as a planned missile launch.

Reports of the planned launch drew fresh U.S. calls for tougher U.N. sanctions that are already under discussion in response to most recent North Korea's nuclear test.

State Department spokesman John Kirby said the United Nations needed to "send the North Koreans a swift, firm message".

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Pyongyang has said it has a sovereign right to pursue a space programme by launching rockets, although the United States and other governments worry that such launches are missile tests in disguise.

A spokeswoman for the International Maritime Organization, a U.N. agency, said the agency had been told by North Korea it planned to launch the 'Kwangmyongsong' satellite.

The International Telecommunication Union, another U.N. agency, also told Reuters North Korea had informed it on Tuesday of plans to launch a satellite with a functional duration of four years in a non-geostationary orbit.

North Korea said the launch would be conducted in the morning one day during the announced period, and notified the coordinates for the locations where the rocket boosters and the cover for the payload would drop.

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Those locations are expected to be in the Yellow Sea off the Korean peninsula west coast and in the Pacific Ocean to the east of the Philippines, Pyongyang said.

U.S. officials said last week North Korea was believed to be making preparations for a test launch of a long-range rocket, after activity at its test site was observed by satellite.

North Korea last launched a long-range rocket in December 2012, sending an object it described as a communications satellite into orbit.

North Korea also said last month it had successfully tested a hydrogen bomb but this was met with scepticism by U.S. and South Korean officials and nuclear experts. They said the blast was too small for it to have been a full-fledged hydrogen bomb.

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