North Korea plans to launch a long-range rocket between December 10 and 22, the North's official news agency said Saturday.

South Korea expressed its grave concern, calling the move a "provocation" and "challenge" to the international community.

In a statement carried by the North's Korean Central News Agency, the Korean Committee for Space Technology said it planned to launch a working satellite after scientists had studied mistakes made during a failed rocket launch in April.

"Scientists and technicians of the DPRK analysed the mistakes that were made during the previous April launch and deepened the work of improving the reliability and precision of the satellite and carrier rocket, thereby rounding off the preparations for launch," it said.

The rocket was intended to put a polar-orbiting earth observation satellite into orbit, it said.

In April, North Korea failed with a much-hyped launch of an Unha-3 rocket that Pyongyang also said was aimed at placing a satellite in orbit.

The U.S. and the U.N. insisted it was a disguised ballistic missile test using a three-stage variant of the Daepodong-2 inter-continental ballistic missile.

The April test put a halt to the latest international effort to engage North Korea, with the U.S. calling off plans to deliver badly needed food assistance.

Seoul warned that If the launch is pushed ahead, North Korea will face a "strong response" from the international community.

"The (South Korean) government expresses grave concern over North Korea's plan to launch a long-range missile again in the name of a working satellite," Foreign Ministry spokesman Cho Tai-young said in a statement.

The international community has long suspected that the communist country may be pushing to test-fire a long-range ballistic missile, as images taken by U.S. satellites showed a marked increase in activity at a North Korean missile launch site in its northwestern tip.

The U.N. Security Council warned the communist nation Thursday not to go ahead with another ballistic missile launch.

"We all agree it would be extremely inadvisable to proceed with the test," Portuguese Ambassador Jose Filipe Moraes Cabral, who heads the North Korea sanctions committee, told reporters.

The North's rocket launch will be seen in South Korea as an attempt to affect its Dec. 19 presidential election. How to handle relations with hostile North Korea is a key campaign issue.

Experts in South Korea note that the North's planned rocket launch may be timed with the first anniversary of the death of its late leader Kim Jong-il on Dec. 17. His son, Kim Jong-un, took over after his father's death.

The North's announcement comes as South Korea is struggling to send its first communications satellite from its own soil. The South Korean rocket launch, scheduled for Nov. 29, has been postponed twice for technical reasons. (From news reports)