Fighter jets roared through the skies over downtown Pyongyang as the world watched to see whether North Korea would defy international warnings and launch a long-range rocket over the Yellow Sea.

The five-day window for the launch of a rocket carrying an observation satellite opened yesterday as North Koreans woke to details about developments at a Workers' Party conference where leader Kim Jong Un ascended to top posts and brought with him a new generation of officials.

His father, Kim Jong Il, was granted the posthumous title of "eternal general secretary" at the special one-day party conference. The immortalisation of the late leader provided a glimpse into how North Korea will handle the nation's second hereditary succession and indicates he will be honoured in much the same way as his father, Kim Il Sung, was made "eternal president" after his 1994 death.

Footage on state TV showed Kim Jong Un seated at the front of the conference with white statues of his grandfather and a new statue of his father in his trademark khaki work ensemble, one arm on his hip. On Mansu Hill, once the domain of a huge bronze statue of Kim Il Sung, a second covered statue awaits its unveiling.

There was no word on the timing of the controversial rocket launch, which the North has said will take place some time between yesterday and Monday.

In 2009, a similar launch from an east coast site took place on the second day of a five-day window.

The United States, Japan, Britain and others say the launch would constitute a provocation and would violate UN Security Council resolutions banning North Korea from developing its nuclear and missile programmes.

Experts say the Unha-3 carrier is similar to the type of rocket that could be used to fire a missile mounted with a nuclear warhead to strike the US or other targets.

The launch and Kim's formal ascension to top posts comes during a week of events leading up to celebrations on Sunday marking the 100th anniversary of the birth of Kim Il Sung.

The centennial is a major milestone in the nation Kim founded in 1948, and the streets of the capital, Pyongyang, were awash with new posters, banners and the national flag. The streets were busy with women clad in traditional Korean dresses and children waving red flags.

The Taedong River flyover of fighter jets was practice for a military parade, officials said. North Korea's army celebrates its 80th anniversary later this month.

The expected satellite launch is one of the marquee events this week. North Korean space officials call the launch of the Unha-3 rocket, mounted with an earth observation satellite, a "gift" to Kim Il Sung. They said on Wednesday that the final step of injecting fuel into the three-stage rocket was under way in the coastal hamlet of Tongchang-Ri.

"We are injecting fuel as we speak," Paek Chang Ho, chief of the space committee's General Command Centre, told reporters given a chance to visit the control centre outside Pyongyang.

He said the rocket would be ready for liftoff as soon as engineers were given the green light. North Korea has informed international aviation, maritime and telecommunications authorities that the launch will take place between yesterday and Monday.

Because liquid rocket fuel is highly volatile and corrosive, its injection into the rocket is usually one of the final steps in the pre-launch process, experts say. But the weather, and particularly the wind, could force delays.

An analysis of recent satellite images shows preparations appear complete, according to the US-Korea Institute at Johns Hopkins School of Advanced International Studies.

Images taken by a commercial satellite earlier in the week revealed increased activity at an instrumentation site that will track and collect data from the rocket to be passed to the launch control centre.

A mobile radar tracking antenna was also removed from its stowed position, indicating it had been checked out for operations. The analysis for the institute's website, 38 North, also says a mobile optical system appears to have been set up to track the rocket's flight.

The planned launch was a focus of discussions among foreign ministers from the Group of Eight leading industrialised democracies.

"I think we all share a strong interest in stability on the Korean peninsula, and we will be discussing how best to achieve that as well," US Secretary of State Hillary Clinton told her colleagues in Washington.

Paek denied that the launch was anything but a peaceful civilian bid to send a satellite into space.

- AP

By Jean Lee