SEOUL, South Korea — South Korea warned on Wednesday of “searing” consequences if North Korea doesn’t abandon plans to launch a long-range rocket that critics call a banned test of ballistic missile technology.

The South’s rhetoric about unspecified harsh consequences comes less than a month after North Korea’s defiant fourth nuclear test and as diplomats at the U.N. work on strong new sanctions against the North.

North Korea on Tuesday informed international organizations of its plans to launch an Earth observation satellite on a rocket between Feb. 8 and 25, and if North Korea’s past patterns are any clue, angry warnings by its neighbors and Washington probably won’t dissuade a coming launch.

The launch declaration, which is meant to warn civilians, shipping and aircraft in the area about the rocket and falling debris, follows North Korea’s disputed claim on Jan. 6 to have tested a hydrogen bomb, the country’s fourth nuclear test. A launch would be seen as a snub by North Korea of its only major ally, China, whose representative for Korean affairs landed in the North for talks on Tuesday.

South Korean and U.S. officials said the launch would threaten regional security and violate U.N. Security Council resolutions that ban the country from engaging in any ballistic activities.

“We warn that if North Korea proceeds with a long-range missile launch, the international society will ensure that the North pays searing consequences for it as the launch would constitute a grave threat to the Korean Peninsula, the region and the world,” senior South Korean presidential official Cho Tae-yong said in televised remarks.

In Washington, Daniel Russel, the top diplomat for East Asia, said the U.S. was tracking reports of the North’s planned launch. He said a launch that uses ballistic missile technology would be another violation of a U.N. ban and strengthens the argument for the international community to impose “real consequences” on North Korea for destabilizing behavior. He called for the imposition of tough additional sanctions.

Russel said a launch “would be an unmistakable slap in face to those who argue that you just need to show patience and dialogue with the North Koreans but not sanctions,” in an apparent reference to China.

China urged restraint Wednesday over North Korea’s announcement of its launch plans, and expressed skepticism over the U.S. calls for tough new sanctions.

“We hope all sides show restraint and take prudent action to avoid any moves that may increase the tensions on the (Korean) Peninsula,” Chinese Foreign Ministry spokesman Lu Kang said at a regularly scheduled news briefing.

Russia, a member of long-stalled six-nation talks on North Korean nuclear disarmament, said in a statement that the North “is displaying glaring disdain for generally recognized norms of international law” by violating U.N. Security Council resolutions, and urged it to “realistically assess all negative consequences of such shortsighted moves.”