The long-range rocket launch by North Korea has failed to deliver as it crashed into the sea minutes after lift-off.

In a rare admission of failure, North Korea's official news agency, KCNA, confirmed that its satellite, launched in defiance of its Asian neighbours and the West, had not reached orbit after the rocket carrying it exploded. Scientists and technicians are looking into what went wrong, according to China's state-run news agency, Xinhua.

The official confirmation followed South Korean and US claims that the rocket had failed.

"South Korean and US intelligence understand that North Korea's missile launch failed," a spokesman for the South Korea's defence ministry Kim Min-seok said.

"At approximately 7:40 am we confirmed that a certain flying object was launched from North Korea and fell after flying for just over a minute. There was no impact on Japanese territory," the BBC quoted Japan's defence minister Naoki Tanaka saying.

The rocket crashed off the west coast of South Korea after flying 120km (75 miles) from its launch site close to the Chinese border, according to Reuters.

"The first stage fell into the sea west of South Korea, and the remainder of the satellite-carrying missile was deemed to have failed. No debris fell on land. At no time were the missile or the resultant debris a threat," the Reuters quoted the North American Aerospace Defense Command, NORAD, as saying.

North Korea went ahead with the rocket launch to mark the 100th birth anniversary of its founde Kim il- Sung, despite the international pressure to back off.

According to Pyongyang, the rocket launch was to place a weather satellite into the orbit. That claim was contested by the US and others who said it was a missile test.

The satellite launch was announced just two months after the North's newly installed leader, Kim Jong-un, agreed to a moratorium on missile testing.

North Korea had agreed to suspend long-range missile tests and uranium enrichment and allow access to UN weapons inspectors to its nuclear programmes, as part of a deal to get 240,000 tonnes of food aid.

Pyongyang is restricted from nuclear and ballistic activity following a 2009 missile launch.

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