By Ju-min Park
SEOUL, Jan 21 (Reuters) - Reclusive North Korea made most of the key parts of the long-range rocket it launched in December, South Korea said on Monday, evidence of home-grown technology moving it a closer to designing a missile system capable of hitting the United States.
The North is banned from carrying out missile and nuclear-related activities under U.N. sanctions and the Security Council is closing on a resolution that will see it punished again for December's launch.
"North Korea is believed to have made a majority of components itself, although it used commercially available products imported from overseas," South Korea's Defence Ministry said in a report.
The North's ultimate aim, Washington believes, is to design an intercontinental ballistic missile capable of carrying a nuclear warhead that could hit the United States, dramatically increasing Pyongyang's military and diplomatic clout.
Pyongyang has continued work on its nuclear testing facilities according to satellite imagery, potentially paving the way for a third nuclear bomb test.
Its prior two tests, in 2006 and 2009, prompted the U.N. sanctions.
South Korea retrieved and analysed parts of the first-stage rocket that dropped in the waters off its west coast.
"Despite component supply and adoption of advanced technologies being limited due to international sanctions, North Korea increased completion of its long-range missile technology through several tests and experiences," the ministry report said.
A South Korean ministry official said no components imported by North Korea appeared to be in breach of the Missile Technology Control Regime, an international norm for missile non-proliferation.
South Korean officials have said the North has likely developed the technology to propel a warhead more than 10,000 km (6,200 miles), putting California within striking distance.
But it is believed to be some way from putting a nuclear warhead on any missile. Experts believe it still needs to fashion a nuclear bomb small enough to fit on to a missile and to secure the technology that would allow it to survive the heat and vibration of re-entering the Earth's atmosphere. (Reporting by Ju-min Park; Editing by Nick Macfie)