North Korea has transported an intercontinental ballistic missile to a new launch site, and has ordered troops on its west coast to double ammunition stocks, South Korea''s Yonhap agency said on Monday.

The agency cited an anonymous South Korean intelligence official as saying vehicle activity to and from military bases along the west coast has increased.

The report follows last week''s sighting of an intercontinental ballistic missile on a cargo train in the reclusive communist state.

The official said North Korea''s military is believed to have moved a missile to its new launch site in Dongchang-ri, in the North Pyongan Province, and could launch it later this month.

"We believe the North could launch the missile at any time after one or two weeks," he said.

Other South Korean media reports said the rocket is a version of the Taepodong-2 missile fired on April 5, when the North claimed to be launching a satellite.

North Korea is banned from nuclear and ballistic tests under United Nations Security Council Resolution 1718, passed in 2006 after the country''s first nuclear test explosion.

The regime has reacted furiously to threats of UN sanctions over last week''s nuclear test, warning of "self-defense measures."

"The world will soon witness how our army and people stand up against oppression and despotism by the UN Security Council and uphold their dignity and independence," the North''s official news agency said on Friday.

The country has also voiced anger over regular overflights by South Korean and American surveillance drones.

The North carried out a series of short-range missile launches last week, in apparent defiance against the UN. Harsh sanctions against the country have been blocked in recent years by Russia and China, veto-wielding members on the Security Council, but both countries are believed to be considering sanctions over the nuclear test.