North Korea's satellite delivered by its long-range rocket was circling the Earth with an orbital period of 95.4 minutes, Seoul's defense ministry said Thursday, but it was not yet known whether it was functioning properly.

A day after the communist state's successful, surprising multistage rocket launch, the defense ministry acknowledged that the Kwangmyongsong-3 satellite was circling the Earth at a speed of

7.6 kilometers per second, citing data by the North American Aerospace Defense Command, or NORAD. The oval radius has a perigee altitude of 505 km and an apogee altitude of 580 km.

"It is not yet known what kind of mission the satellite is conducting," the ministry spokesman Kim Min-seok said in a briefing. "It usually takes two weeks to evaluate whether a satellite is successful. For the time being, it is working normally."

Although the communist state claims Wednesday's launch was meant to send a peaceful satellite into space, the South Korean government sees it as a covert test for ballistic missile technology and the launch means it is a step closer to perfecting an intercontinental ballistic missile, Kim said.

The three-stage rocket has an estimated range of 10,000 kilometers, Kim said, which can fly over the Pacific Ocean to hit the U.S.

"If the North replaces the satellite with a nuclear war head, it could turn into an intercontinental ballistic missile," Kim said.

The Korean Aerospace Research Institute (KARI) also confirmed the satellite has been placed on an elliptical orbit, citing the NORAD data, though Pyongyang had intended to put it on a circular orbit with a radius of 500 km.

 "If the satellite circles an oval orbit, not a circular orbit, the duration of continuous shooting is lengthened in certain regions," said Lee Kyu-su, a public relations official at the KARI.

 While a large satellite can correct its path with the help of a small booster, the North's 100-kg satellite is not equipped with such equipment, and thus will be stuck in an elliptical orbit, Lee said.

Since Pyongyang has tested two nuclear devices since 2006, it has been upgrading its atomic technology to conduct another test "when time is ready," he said.

The South Korean military has deployed Aegis warships and minesweeping ships in the western sea to search for the debris.

With search operations under way, the South Korean Navy earlier in the day recovered debris from the rocket's first stage in the Yellow Sea, according to officials, which is in accordance with the trajectory announced by the North.

The rocket's first part fell in waters west of the Korean Peninsula, while the second part landed in the sea east of the Philippines, about 2,600 kilometers away from the launch site.

Although the debris could give an early glimpse of the rocket's components and capability, the military has no plan to disclose the details citing military information, they noted.

Ahead of the launch, the North had sent missile scientists and equipment to some Asian nations in late November, such as China, Mongolia and Indonesia, according to the Washington-based Radio Free Asia and a senior source in Seoul.

"It appears that the equipment set up in China and Mongolia is aimed at tracking the satellite," spokesman Kim said. "Because the satellite circles very fast, it briefly passes through North Korea.

Therefore, several regions need antennas to track it." (Yonhap News)