North Korea hinted Monday at a possible satellite launch, fuelling speculation that it might attempt to fire a long-range rocket to coincide with a key political anniversary next month.

Any such launch would invite fresh international sanctions and jeopardise a reunion being organised with South Korea of families divided by the 1950-53 Korean War.

The North insists its rocket launches are intended to put peaceful satellites into orbit, while the US and its allies see them as disguised ballistic missile tests.

In an interview with the state-run KCNA news agency, the director of the North's National Aerospace Development Administration said Pyongyang was in the "final phase" of developing a new geo-stationary satellite.

"The world will clearly see a series of satellites ... soaring into the sky at the times and locations determined by the (ruling Workers' Party) central committee," the director was quoted as saying.

Space development is a sovereign right that North Korea intends to exercise "no matter what others might say about it," he added.

He made no mention of any specific schedule, but there has been widespread speculation that the North might launch a satellite to mark the 70th anniversary of the Workers' Party founding on October 10.

Expert analysis of recent satellite images suggest North Korea has completed upgrades at its main Sohae satellite launch site.

Analysts at the US-Korea Institute at Johns Hopkins University believe the launchpad at Sohae is now capable of handling rockets up to 50 metres (165 feet) in length -- almost 70 percent longer than the Unha-3 rocket the North sent into space in December 2012.

However, the same analysts have stressed that none of the satellite images examined so far have shown activity to suggest a rocket launch might be imminent.

North Korea is banned under UN Security Council resolutions from carrying out any launch using ballistic missile technology, although repeated small-range missile tests into the sea have gone unpunished.

The Unha-3 launch nearly three years ago resulted in fresh sanctions and a surge in military tensions that culminated three months later in the North conducting its third nuclear test.

If the North does go ahead with a rocket launch on or around the ruling party anniversary, it would almost certainly scupper an inter-Korean family reunion planned for October 20-26.

The decision to hold a reunion was part of an inter-Korean deal struck last month after cross-border tensions came close to boiling over into outright conflict.