North Korea says it will carry on its "important duty," as planned, to monitor the military maneuvers of the United States and other hostile forces to enhance its space reconnaissance capabilities.

Countries concerned are on heightened alert as the North is believed to be preparing for another military spy satellite launch in the near future.

North Korea revealed plans to launch three more military spy satellites this year, following what it calls a successful launch of its first military satellite, the Malligyong-1, last November.

North Korea's National Aerospace Technology Administration, which is responsible for launching military reconnaissance satellites, released its spokesperson's statement through the state-run Korean Central News Agency on Saturday.

The administration criticized the launch of South Korea's second spy satellite from the United States this month, and said the North's space development project, including military satellite launch, is a "strategic choice indispensable for guaranteeing our country's security, interests and right to existence."

A US think tank says satellite images of North Korea's Sohae satellite-launching station in the country's northwest show that preparations are underway to proceed with another spy satellite launch in the near future.