* Launch appears to have been successful: expert
* North Korea says "complete success"
* U.N. Security Council likely to hold Sunday emergency meeting
* U.S., Japan, South Korea condemn launch
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 U.N. sanctions and just weeks after a nuclear bomb test.
The U.S. 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.
North Korea's last long-range rocket launch, in 2012, put what it called a communications satellite into orbit, but no signal has ever been detected from it.
"Everything we have seen is consistent with a successful repeat of the 2012 (launch)," said U.S. missile technology expert John Schilling.
"But it's still too early to tell for sure," said Schilling, who is involved in the "38 North" North Korean monitoring project at Johns Hopkins University.
The rocket was launched at around 9:30 a.m. Seoul time (0030 GMT) in a southward trajectory, as planned. Japan's Fuji Television Network showed a streak of light heading into the sky, taken from a camera at China's border with North Korea.
North Korea had notified U.N. agencies that it planned to launch a rocket carrying an Earth observation satellite, triggering opposition from governments that see it as a long-range missile test.
The U.N. Security Council was likely to hold an emergency meeting on Sunday to discuss the launch, at the request of the United States, Japan and South Korea, diplomats said.
The United States was tracking the rocket launch and said it did not believe that it posed a threat to the United States or its allies, defence officials said.
Isolated North Korea had initially given a Feb. 8-25 time frame for the launch but on Saturday changed that to Feb. 7-14, apparently taking advantage of clear weather on Sunday.
North Korea's National Aerospace Development Administration called the launch "an epochal event in developing the country's science, technology, economy and defence capability by legitimately exercising the right to use space for independent and peaceful purposes".
The United States will work with the U.N. Security Council on "significant measures" to hold North Korea to account for its launch, U.S. Secretary of State John Kerry said.
Calling the launch a flagrant violation of U.N. resolutions on the country's use of ballistic missile technology, Kerry reaffirmed the "ironclad" U.S. defence commitments to allies Japan and South Korea and called the launch a destabilising and unacceptable challenge to peace and security.
South Korean President Park Geun-hye called the launch an unforgivable act of provocation.
Japanese Prime Minister Shinzo Abe called the launch "absolutely unacceptable", especially after North Korea had tested a nuclear device last month.
"To launch a missile after conducting a nuclear test goes against the U.N. resolution. We will respond resolutely, coordinating closely with the international community," he told reporters.
Japan had said that it was ready to shoot down the rocket if it had posed a threat to it, but did not take any action, Japan's NHK reported.
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.