North Korea has confirmed it will conduct a rocket launch imminently, angering neighbours and the US, who are worried that Pyongyang's real intention is to advance its missile technology under the guise of a satellite programme.

The US called for tougher sanctions against North Korea, while South Korea said any rocket launch will be a breach of UN resolutions and a "direct challenge" to the international community.

"Should the North push ahead with the long-range missile launch ... it would have to pay the price dearly," South Korean government said in a statement.

Japanese Prime Minister Shinzo Abe condemned the North leadership, saying the launch plan was a "serious provocation."

Earlier, the International Maritime Organization, a UN agency, said it had received notification from Pyongyang about the rocket launch.

"We have received information from DPRK regarding the launch of earth observation satellite 'Kwangmyongsong' between 8-25 February," a spokeswoman said, according to Reuters.

North Korea insisted the planned rocket launch, which will take place between February 8 and 25, is part of its space programme. The US and its allies say Pyongyang is pushing ahead with the development of an inter-continental ballistic missile.

Pyongyang's admission that it is planning a rocket launch comes after days of speculation about an imminent missile launch.

Analysis of satellite imagery had detected increased acidity at North's secretive Sohae Satellite Launching Station at Tongchang-ri.

Following this Japan put its self defence forces on alert for a potential ballistic missile launch, with instructions to destroy any missile fired in its direction.

On January 6 North Korea said it conducted a successful testing of a hydrogen bomb, worsening the security scenario in the region.