The humiliating failure of North Korea's much-publicised rocket launch may push the hermit state into testing a nuclear bomb in an attempt to save face, analysts said Friday.

Touted as a glorious demonstration of North Korean technology to mark the centenary of the birth of founding leader Kim Il-Sung, the rocket turned into a damp squib when it crashed into the sea.

The 30-metre (100-foot) Unha-3 (Galaxy-3) rocket blasted off early Friday morning from a newly built space centre on the country's northwestern coast.

But shortly after launch it broke apart and the debris fell into the Yellow Sea off South Korea, the South's Yonhap news agency quoted a high-ranking military source as saying.

"North Korea executed its highly anticipated missile launch and with its failure managed to achieve the second-worst outcome imaginable. The worst would have been hitting China," Marcus Noland of the Washington-based Peterson Institute for International Economics wrote in a blog post.

"The North Koreans have managed in a single stroke to not only defy the UN Security Council, the United States, and even their patron China, but also demonstrate ineptitude."

North Korea invited up to 200 foreign journalists to Pyongyang for the launch and the centenary commemorations on the weekend, the largest number of overseas media ever welcomed in to the reclusive state.

The humiliation of the rocket failure will be keenly felt by new leader Kim Jong-Un -- who took over after his father, Kim Jong-Il, died in December -- said Toshimitsu Shigemura, North Korea expert and professor at Waseda University in Tokyo.

"What the young leader of North Korea lacks most is legitimacy. He is the blood-related son of Kim Jong-Il and Kim Il-Sung. But he has no achievement, which was troublesome," said Shigemura.

"In order to make him legitimate, he needed a successful satellite or missile launch. But it ended in a failure."

Shigemura said North Korea would not have been able to hide the flop from its citizens because of the presence of tens of thousands of Chinese tourists and business people with mobile phones.

He said authorities are now faced with the difficult task of stemming an inevitable sense of disappointment before it becomes a threat to the regime.

"Starting today or tomorrow in Pyongyang, rumours will start that the new leader has failed to impress and is no good," he said.

"Kim Jong-un and the leadership will have to take measures to make up for that, either by providing food or building new housing. They have to do something to show real achievement."

The Washington-based Noland said a nuclear test was now all but inevitable.

"Before the launch, it was probable that North Korea would conduct a third nuclear test; now it is a virtual certainty."

Analysts say satellite imagery showing what looks like preparations, and the communist regime's previous patterns of behaviour -- with missile tests followed by bomb tests -- suggest a third nuclear test could be imminent.

Rory Medcalf, international security programme director at the Lowy Institute think-tank in Australia, said the regime's plans to test a uranium-fuelled nuclear device could be pushed forward.

"I will not say definitively that we are going to see a nuclear test or some other provocation but I think the chances are higher today than they were yesterday," he told AFP.

North Korea has said the rocket launch was a peaceful attempt to put a satellite into orbit but the United States, South Korea and Japan have condemned it as a poorly disguised ballistic missile test.

UN resolutions ban the North from testing long-range missiles that could be used to launch a satellite or a nuclear warhead.

The North is believed to have six to eight plutonium-fuelled atom bombs, and analysts say it is working on a uranium-based device. It last conducted a nuclear test in 2009.

Jingdong Yuan, acting director at the Centre for International Security Studies at the University of Sydney, said that if the country's military leaders wanted to push on with a nuclear test "they will have their way".

But the temptation will be weighed against the risk that another embarrassing failure will ruin the centennial celebrations, he said.

IHS Jane's managing director Tate Nurkin said the "biggest concern about North Korea is their weakness not their strength".

"We don't think that North Korea is seeking conflict. They are seeking attention and the concessions that come with that attention that can help prop up the regime," he said in a statement.