Pyongyang has invited the European Space Agency and space agencies from eight countries including the US, Japan, China, Russia and India to observe its planned satellite launch some time next week, a Japanese news report said.

The National Aeronautics and Space Administration of the US and the Japan Aerospace Exploration Agency rejected the offer, Kyoto News said.

The Japanese government is encouraging Russia and China to follow suit, it said.

The Russian Federal Space Agency said it would not dispatch its experts to attend either, saying the launch would violate the UN Security Council Resolution 1874 which Russia supported, sources said.

The US urged the international community not to take any action regarding Pyongyang's invitation, saying it could be seen as legitimizing the rocket launch.

"We call on the international community to abstain from taking any actions, such as sending observers, that might be seen as endorsing a launch that would be in blatant defiance of the DPRK's international obligations and commitments,"  a State Department official was quoted as saying by the Yonhap news agency. DPRK refers to the Democratic People's Republic of Korea.

Pyongyang says it will go ahead with its plan to launch a rocket to put a satellite into orbit between April 12 and 16, citing its sovereign right to space development.

The US and its allies see it as a pretext to test a long-range ballistic missile.

US Secretary of State Hillary Clinton said Washington will keep pressing to end Myanmar’s military relationship with Pyongyang.

Within the US government and Congress, suspicion has been raised that Myanmar might be cooperating with North Korea in military areas including development of nuclear weapons.

Satellite images showed that Pyongyang's rocket will be in place within days, said Allison Puccioni, image analyst at HIS Jane’s Defence Weekly.

"The level of activity at the launch pad and tower indicates that the rocket should be in place within days,"  Puccioni said in a report.

The Kwangmyongsong-3 is to be launched at a Dongchang-ri facility on the western side of the Korean peninsula.

Previously, Pyongyang had launched rockets from the Musudan-ri facility on the eastern side of the peninsula.

The Dongchang-ri facility has a larger launch tower than the facility in Musudan-ri, allowing larger rockets including intercontinental ballistic missiles to be fired.

Located 70 kilometres away from the Yongbyon nuclear complex, the Dongchang-ri facility is more accessible to nuclear materials.