By Jack Kim and Kim Yeon-hee
SEOUL (Reuters) - North Korea appeared to launch a rocket on Sunday, the Japanese government said, defying calls from world leaders to scrap a plan that has caused international alarm.
It was not immediately clear if the launch had been successful, or if it was a long-range version of the rocket.
The rocket is supposed to fly over Japan, dropping boosters to its west and east on a path that runs southwest of Hawaii.
The United States, South Korea and Japan say the plan is actually the test of a Taepodong-2 missile, which is designed to carry a warhead as far as Alaska.
U.S. President Barack Obama said on Friday the international community would take action if North Korea went ahead with the launch to show Pyongyang it could not act with impunity.
Impoverished North Korea, which for years has used military threats to wring concessions from regional powers, has said it is putting a satellite into orbit as part of a peaceful space programme and threatened war if the rocket was intercepted.
Sunday is the second day in the April 4-8 timeframe the secretive North, which tested a nuclear device in 2006, had set for the launch. In its only previous test flight, in July 2006, the Taepodong-2 blew apart about 40 seconds after launch.
Poor weather and planning may have forced North Korea to delay the launch on Saturday, officials in Seoul said, after Pyongyang had reported preparations were complete and lift-off would take place soon.
Experts have said clear visibility would help North Korea, with limited radar capabilities, monitor the flight.
Before the launch, the Kyodo news agency quoted Japanese Foreign Minister Hirofumi Nakasone as saying the authorities were on alert and had made "every preparation."
Japan has dispatched missile intercepting-ships and anti-missile batteries along the projected flight path.
Tokyo said it would not intercept the missile but it was ready to shoot down any debris, such as falling booster stages, that may threaten its territory.
A BOOST FOR KIM
Analysts said the launch may help North Korean leader Kim Jong-il shore up support after a suspected stroke in August raised questions of his grip on power and bolster his hand in using military threats to win concessions from global powers.
The United States, Japan and South Korea will view the launch as a violation of a U.N. Security Council resolution passed in 2006 after Pyongyang carried out the nuclear test and other missile tests.
That resolution, number 1718, demands North Korea "suspend all activities related to its ballistic missile programme."
U.N. Security Council diplomats have told Reuters on condition of anonymity that no country was considering imposing new sanctions but the starting point could be discussing a resolution for the stricter enforcement of earlier sanctions.
Both Russia and China, the latter the nearest the reclusive North has to a major ally, have made clear they would block new sanctions by the Council, where they have veto power.
(Additional reporting by Jon Herskovitz in Seoul and Linda Sieg in Tokyo, Editing by Dean Yates and Jeremy Laurence)