Seoul, May 24 (IANS): South Korea's military has detected suspected signs of North Korea making preparations to launch a military spy satellite, an official said on Friday.

In December, Pyongyang vowed to launch three more spy satellites this year, a month after successfully placing its first one into orbit, Yonhap News Agency reported.

South Korea's Defence Minister Shin Won-sik told reporters earlier this year that the North's Malligyong-1 spy satellite appears to be orbiting Earth without activity.

"As apparent signs of preparations for the launch of North Korea's purported military spy satellite have recently been detected in the Tongchang-ri area, South Korean and U.S. intelligence authorities are closely monitoring and tracking related activities," the Joint Chiefs of Staff official said.

The North staged all three of its launches last year from its satellite launch station in Tongchang-ri in the northwestern province of North Pyongan.

While the military has continuously detected activities of personnel, vehicles and equipment at the launch site, they have apparently grown larger in scale recently, reports Yonhap News Agency.

Equipment used to measure and assess the launch trajectory of a space rocket is said to have been detected at the site.

The military has currently strengthened surveillance and monitoring of the area, with preparations being made to intercept the North's launch vehicle if it enters South Korean airspace, the official said.

If the North presses ahead with a launch, it is expected to notify Japan of its schedule as it did prior to all three of its satellite launches last year.

The suspected preparations come as the leaders of South Korea, China and Japan will hold a trilateral summit in Seoul on Monday for the first time in 4 1/2 years, spawning speculation the North could time the launch to coincide with the meeting to maximize its political impact.

South Korea, the United States and others have condemned the North's space rocket launches, calling them violations of U.N. Security Council resolutions banning it from ballistic missile launches, as they use the same technologies.