Japan said Thursday it had shot down a mock missile in the US desert, taking another step to build a shield with the United States against a possible North Korean attack.

Japan became the first country other than the United States to test the new US-developed Patriot Advanced Capability-3 (PAC-3), a surface-to-air missile that tracks and hits incoming targets, the defence ministry said.

In the test Wednesday in the southwestern US state of New Mexico, Japan's air force shot down a mock missile that was launched from 120 kilometres (75 miles) away, a defence ministry spokesman said.

"The success of the test was significant as it proved that Japan's missile defence system will function effectively," the spokesman said.

In an irony of history, the White Sands range of Wednesday's missile test stands on the site where the United States conducted a key 1945 test to make the atomic bomb, which was later dropped on Japan.

Japan has been officially pacifist since defeat in World War II but has increasingly sought to play a larger role in security.

Washington and Tokyo have been working jointly to erect a missile shield against possible attacks from North Korea, which fired a missile over Japan's main island in 1998 and tested an atom bomb in 2006.

A South Korean newspaper said this week that North Korea, at a standstill with the United States over a disarmament deal, had carried out an engine ignition test for a missile believed capable of reaching the US west coast.

US military forces stationed in both Japan and South Korea have deployed PAC-3 missiles.

Japan in December carried out on a separate test in the Pacific Ocean of a Standard Missile 3 (SM-3) sea-to-air missile.

Japan plans to complete its missile shield by early 2011, deploying the PAC-3 missiles at 11 bases and setting up SM-3 missiles on four Aegis warships.