North Korea launched a long-range rocket on Sunday carrying what it has called a satellite, but its neighbours and Washington denounced the launch as a missile test, conducted in defiance of UN sanctions and just weeks after a nuclear bomb test. The US Strategic Command said it had detected a missile entering space, and South Korea's military said the rocket had put an object into orbit, quashing earlier media reports indicating the it might have failed in flight. North Korea said the launch of its satellite Kwangmyongsong-4, named after late leader Kim Jong Il, was a "complete success" and that it was making a polar orbit of the earth every 94 minutes. The launch order was given by his son, leader Kim Jong Un, who is believed to be 33 years old.

U.N. Secretary-General Ban Ki-moon strongly condemned the launch and urged North Korea to "halt its provocative actions", his office said in a statement.

China's Foreign Ministry expressed regret and called on all sides to act cautiously and refrain from taking steps that might further raise tension on the Korean peninsula.

China is North Korea's main ally, although it disapproves of its nuclear weapons programme.

"China expresses regret that North Korea, in spite of the pervasive opposition of the international community, insisted on using ballistic missile technology to carry out a launch," ministry spokeswoman Hua Chunying said in a statement.

North Korea has said that its most recent nuclear test, its fourth, on Jan. 6, was of a hydrogen bomb. However, the United States and other governments have expressed doubt over that claim.

North Korea is believed to be working on miniaturising a nuclear warhead to mount on a missile, but many experts say it is some time away from perfecting such technology.

It has shown off two versions of a ballistic missile resembling a type that could reach the U.S. West Coast, but there is no evidence the missiles have been tested.

North Korea says it has a sovereign right to pursue a space programme.