North Korea has carried out an engine ignition test for a missile believed to be capable of reaching the US west coast, a South Korean newspaper said Tuesday.

Chosun Ilbo, quoting intelligence sources, said the engine was presumed to be for the Taepodong-2 missile with a range of 6,700 kilometres (4,150 miles).

It said the test was conducted at a missile launch site being developed on the west coast whose existence was publicly reported last week.

"A US spy satellite, KH-12, spotted that rocket engine tests took place at Tongchang-ri this year," one source told Chosun, adding the site was near completion.

Another source told the paper the communist North had sporadically conducted engine tests in a continuing attempt to develop long-range missiles since its failed test-firing of a Taepodong-2 in July 2006.

North Korea has a separate site at Musudan-ri on the east coast which was used to launch a Taepodong-1 missile in 1998 over Japan. The Taepodong-2 missile was launched from there in 2006 but US officials said it failed after about 40 seconds.

The North conducted a nuclear weapons test in October 2006. It is not known whether it has the technical capacity to fit an atomic warhead to a missile.

Chosun said work began several years ago on the new site on the west coast in North Pyongan province opposite China and it would be completed next year.

The defence ministry and the National Intelligence Service refused to comment on the report.

Defence Minister Lee Sang-Hee told parliament on Thursday Seoul was closely watching the new missile launch site, which was 80 percent completed.

John Pike, director of research group GlobalSecurity.Org, told US reporters last week the new site was designed to support a significant flight test programme.

"It is significant because it indicates an intention to develop a capability of developing a reliable ICBM (intercontinental ballistic missile)," Pike said.

Pike said the new site was much larger, more elaborate and had better transport connections than Musudan-ri. "It is set up to do a launch three or four times a year, rather than every decade," he said.

He said the main launch pad on the west coast appeared a year or two away from completion.