North Korea's heralded long-range rocket test ended in failure on Friday, disintegrating in mid-air soon after blastoff and plunging into the sea in a major embarrassment for the reclusive state.

The defiant launch drew condemnation from world leaders who described it as a “provocative” act that threatened regional security, despite Pyongyang insisting it was intended to put a satellite into orbit for peaceful purposes.

Some four hours after the rocket exploded over the Yellow Sea, the North admitted the satellite had failed to enter orbit, and that “scientists, technicians and experts are now looking into the cause of the failure”.

The United States and its allies slammed the exercise as a disguised ballistic missile test that contravened U.N. resolutions triggered by Pyongyang's two nuclear tests.

“North Korea is only further isolating itself by engaging in provocative acts, and is wasting its money on weapons and propaganda displays while the North Korean people go hungry,” said White House spokesman Jay Carney. He said the launch “violates international law and contravenes its own recent commitments”, under which Pyongyang had agreed to suspend its nuclear and missile tests in return for U.S. food aid. United Nations chief Ban Ki-moon condemned the launch as “deplorable”, saying it “defies the firm and unanimous stance of the international community”.

South Korea's Defence Ministry said the rocket lifted off at 07:39 a.m. (2239 GMT Thursday) and flew for just over two minutes before it “splintered into two parts, probably due to a blast”, and then broke into smaller pieces.

The debris fell into the Yellow Sea off South Korea and its navy launched a salvage operation to retrieve the debris, despite warnings from Pyongyang last week not to attempt such an operation.

The South said it was keeping a close eye on the North “for further provocative acts such as missile tests and a nuclear test”.

The European Union joined governments in Japan and South Korea in condemning Friday's move as a provocation that undermined peace and security in the volatile Korean peninsula and the wider region.

The North's sole major ally, China, was more muted in its reaction, calling for restraint from all sides and saying it had not been given advance warning of the launch.

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