The three-stage rocket was confirmed to have put an object into orbit but it has not yet been verified whether the alleged satellite is functioning, he told journalists, speaking on condition of anonymity.

The rocket was similar to the Unha-3 launched in December 2012 but is believed to have a range of 12,000 kilometres. The old model was estimated to have a range of some 10,000 kilometres.

There had been speculation the North might use a much larger rocket this time after having completed work on an extended 67-metre gantry tower capable of handling a launch vehicle twice the size of the 30-metre Unha-3.

North Korea, however, has not yet mastered key technology needed to turn the rocket into an inter-continental ballistic missile - a re-entry vehicle to protect the warhead from heat, the official said.

The rocket, carrying an Earth observation satellite, blasted off on Sunday at around 9 am (Pyongyang time) (0600 IST) and, according to North Korean state TV, achieved orbit 10 minutes later.

The launch, widely seen as a disguised long-range missile test, sparked international condemnations and resulted in an agreement at the UN Security Council to impose new sanctions against the increasingly defiant state.

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