SEOUL, South Korea - North Korea has built an underground fuelling facility near a key launch pad, a news report said Thursday, making it harder for spy satellites to detect signs that a missile is being prepared for launch.

The facility was built at the Musudan-ni missile site on North Korea's northeastern coast either late last year or early this year, the Dong-a Ilbo newspaper reported, citing an unidentified senior South Korean official.

The National Intelligence Service, Seoul's top spy agency, and the Defense Ministry declined to confirm the report, citing the sensitivity of intelligence matters.

North Korea announced earlier this week that plans to send a communications satellite into orbit as part of its space program were fully under way. It did not say when the launch would take place, but recent satellite imagery showed brisk activity near the launch pad.

Neighboring powers and the U.S. believe the satellite launch may be a cover for a test-fire of a long-range ballistic missile.

"Our scientists and engineers are actively pushing forward on a peaceful space project," the North's Korean Central Broadcasting Station said in a report late Wednesday.

In 1998, North Korea test-fired a long-range Taepodong-1 ballistic missile over Japan and then claimed to have put a satellite into orbit. In 2006, the country also test-launched a longer-range Taepodong-2 missile believed capable of reaching Alaska, but it plunged into the ocean shortly after liftoff. The North is believed to be working on an upgraded Taepodong-2 capable of reaching the U.S. west coast.

The U.N. Security Council passed a resolution in 2006 prohibiting Pyongyang from ballistic activity. South Korea says it would consider either a satellite or missile launch a threat and violation of the U.N. ban since both use similar rocket delivery systems.

"We expect the North to claim a satellite launch after firing a missile," South Korean Foreign Ministry spokesman Moon Tae-young told reporters Thursday, noting that the North has little need for a satellite in space.

Senior NIS officials told South Korean lawmakers Wednesday that the government suspects the projectile being prepared for launch is a long-range missile, not a satellite.

The object's shape "is similar to" the Taepodong missile, senior NIS officials said, according to ruling party lawmaker Lee Cheol-woo, who attended the closed-door session.

Analysts said satellite imagery taken last week revealed a flurry of activity at the Musudan-ni test site but no indication a rocket had been mounted on the launch pad. Once mounted, the rocket could take days to fuel.

Changes in commercial satellite images captured Wednesday by DigitalGlobe indicate progress toward a launch, said Tim Brown, director of Talent-Keyhole.com, an independent imagery analysis firm in the U.S. He predicted a launch within weeks.

Meanwhile, North Korean leader Kim Jong Il visited towns in the same province as the launch site, about 110 miles (180 kilometers) away, state-run media said Wednesday.