North Korea on Tuesday put the finishing touches to its latest rocket ahead of a politically charged launch that will defy a swelling chorus of international concern including in China and Russia.

With regional airlines and shipping going on alert, and Japan deploying its anti-missile systems, the impoverished but nuclear-armed North said it was set to install the rocket's satellite payload.

"We are expecting to complete assembly by today," Ryu Kum-Chol, a senior member of the communist state's Committee for Space Technology, said in a briefing for foreign journalists in Pyongyang.

The launch is scheduled between April 12 and 16 to mark the 100th anniversary of the birth of North Korea's founding leader Kim Il-Sung, a significant date as Kim's youthful grandson Kim Jong-Un cements his own power.

Tens of thousands in the tightly regimented state have been sprucing up the capital Pyongyang for mass festivities commemorating Sunday's anniversary, which follows the death in December of Jong-Un's father Kim Jong-Il.

Foreign journalists, granted entry to North Korea in rare numbers for the commemorations but dogged as ever by minders, have seen rehearsals for songs and dances, punctuated by living tableaux and processions of floral floats.

The celebrations look set to climax with a parade to show off the regime's military might, in a country where the armed forces enjoy the lion's share of state resources while millions, according to UN agencies, go malnourished.

The rocket launch is the centrepiece of the commemorations, but the United States and other nations say it is a pretext for a ballistic missile test, in defiance of UN resolutions and a recently sealed US-North Korean deal.

Once the satellite is placed on the third and final stage of the fuselage, the 30-metre (100-foot) rocket will need only fuelling before it is ready for liftoff from its platform on the Yellow Sea coast in the country's northwest.

North Korea says the rocket will propel the 100-kilogram (220-pound) Kwangmyongsong-3 (Shining Star) satellite into orbit to collect data on forests and natural resources within its territory.

"The right to have a satellite is a universal right of every nation on this planet," Ryu said. "We do not recognise any UN resolution that violates our sovereignty."

But Russia joined the international condemnation on Tuesday, saying the planned launch was "an example of disregard" for UN Security Council resolutions on North Korea's nuclear and weapons programmes.

South Korean officials believe the launch will be followed by North Korea's third nuclear test. The North tested atomic weapons in October 2006 and May 2009. Both detonations were held after missile tests.

North Korea says it first managed to place a satellite in orbit in April 2009, although international observers dispute that, saying that rocket launch also masked a ballistic missile test.

China, North Korea's sole diplomatic and economic patron, again issued a veiled admonishment of Pyongyang by urging all parties to "exercise restraint" and avoid an escalation of tensions on the Korean peninsula.

The United States wants China to go much further, demanding that Beijing force Pyongyang to call off the launch.

US Defense Secretary Leon Panetta and South Korean Defence Minister Kim Kwan-Jin agreed in a telephone call Tuesday to take coordinated action against the "grave provocation" of the launch, the defence ministry in Seoul said.

South Korea convened a meeting of top security officials including the ministers of defence, foreign affairs and unification. The foreign ministry said the UN Security Council would likely convene to discuss subsequent steps.

Japan has deployed missile batteries in central Tokyo and dispatched destroyers after Prime Minister Yoshihiko Noda gave the green light to shoot down the rocket if it threatens Japan's territory.

Vessels have been warned to stay out of shipping lanes that might fall under the rocket's path, while at least three airlines -- Japan Airlines, All Nippon Airways and Philippine Airlines -- are diverting some routes.

The North Korean official insisted that the rocket posed no danger to countries in the region.

"We've chosen a safe trajectory. The first stage will fall 100 miles (160 kilometres) from land (in the Philippines), and the second stage 120 miles from land," Ryu said.

But if the rocket should veer off course, the official said it was "capable of self-destruction" from ground control.