South Korea prepared on Tuesday to launch its first rocket, just four months after rival North Korea defiantly launched its own and quickly was slapped with UN sanctions.

The North has warned it would closely watch the international response to South Korea's launch on Wednesday.

In April, the North claimed it shot a satellite into orbit and was angered when the US, Japan and South Korea called it a disguised test of the regime's UN-banned ballistic missile technology.

South Korean officials have said their rocket launch, carrying an observation satellite, is peaceful, and they hope it will boost the country's aim to become a regional space power.

The launch of its first rocket, built in cooperation with Russia, was to take place from its space center on an island about 465 kilometers south of Seoul, according to the Science Ministry.

If successful, it would also mark South Korea's first launch of a rocket into space from its own territory. Since 1992, it has launched 11 satellites from overseas sites, all on foreign-made rockets.

Science Ministry official Yeom Ki-su said the two-stage rocket, called KSLV-I, will carry a domestically built satellite aimed at observing the atmosphere and ocean.