North Korea concludes investigation into failed rocket launch

Hong Kong (CNN) -- North Korea says its scientists have concluded their investigation into the failure of the country's long-range rocket launch last week, but it declined to divulge why the flight ended in a trail of debris strewn across the sea.

Experts have "wound up the specific and scientific probe into the cause" of the rocket's failure to put a satellite into orbit, the official Korean Central News Agency said in a report late Thursday without elaborating on what the cause was.

Pyongyang had insisted that the purpose of the launch was to send an "earth observation satellite" into space. But the United States, South Korea and Japan called the operation a ballistic missile test in disguise.

North Korea's Kim Jong Un speaks

"All the scientific and technological data and precious experience gained this time will serve as a very precious boon to space development and a reliable guarantee for greater success in the days ahead," the KCNA report said, citing an unidentified spokesman for the Korean Committee for Space Technology.

How NK leaders reacted to launch failure

The rocket flew for only about a minute and half after its take off on April 13 before it broke into pieces above the Yellow Sea.

On Monday, the U.N. Security Council condemned the failed launch, saying it was "a serious violation" of previous council resolutions and "has caused grave security concerns in the region."

North Korea said in the state media report Thursday that it had "never recognized" the U.N. resolution on the matter, describing it as "a product of sinister intentions of the hostile forces."