U.N. Secretary-General Ban Ki-moon says North Korea's plan to launch a long-range rocket next month threatens regional peace.
Ban says the plan is undermining a "positive atmosphere" established recently by the U.S. and North Korea.
Pyongyang says it will launch an observation satellite on the rocket. Other countries fear it wants to test long-range missile capabilities.
Ban told reporters Thursday while visiting Malaysia that the launch would be a "clear violation" of a U.N. resolution.
Ban urged Pyongyang to "refrain from any such acts which will destabilize peace and security in the Korean peninsula."
He said he has contacted countries to exercise influence on Pyongyang and would engage leaders at next week's Nuclear Security Summit in Seoul.