North Korean leader Kim Jong-un has ratcheted up his regime's militaristic rhetoric as Pyongyang threatened to retaliate against any country that intercepts a North Korean rocket booster or collects the rocket debris.

The North has vowed to launch a rocket sometime between April 12 and 16 to put an earth observation satellite into orbit, a move widely seen as a pretext to disguise a banned test of its ballistic missile technology.

The Committee for the Peaceful Reunification of Korea in Pyongyang warned that interception of the satellite would be "an act of war" and would cause a tremendous catastrophe.

Whoever "intercepts the satellite or collects its debris will meet immediate, resolute and merciless punishment" from the North, the committee said in an English-language statement carried by its Korean Central News Agency late Thursday.

The warning came days after South Korea said it was exploring measures to intercept the rocket booster in case it veers off its trajectory. Japan has also ordered its troops to shoot down the rocket if there is concern it or parts of it could land on Japan.

South Korea expects the rocket's first-stage booster to land in international waters, some 170 kilometers south of its southwestern city of Gunsan, before the rocket's second stage booster falls east of the Philippines.

The North has said it chose a safe flight path to ensure carrier rocket debris jettisoned during the flight will not impact on neighboring countries.

The statement also warned South Korea against any provocation, noting any attack by Seoul on Pyongyang would mean the "end of everything in Korea."

Korea is within striking distance of North Korea's missiles. Seoul, the South Korean capital city of more than 10 million people, is also within range of North Korea's conventional artillery.

North Korea "will mete out the unimaginable and the most miserable punishment to its rival if it dares fire into the sky above the (North), Pyongyang, in particular," the statement said.

The North's threat came after South Korea vowed it would attack the North's capital in retaliation if the communist country strikes Seoul.

Korea has set up a policy of tit-for-tat retaliation in dealing with possible aggression by the North against Seoul and adjacent areas.

South Korea came under public fire for its weak response to the North's deadly shelling of a South Korean western border island in November 2010.

Meanwhile, North Korean leader Kim has also ordered his troops to bury the nation's enemies at sea if they "dare intrude into the territorial waters" of the North. Kim made the comment during his inspection trip to a navy unit that seized a U.S. spy ship, Pueblo, in 1968, the KCNA said in a dispatch on Friday.

Kim, who took over the country following his father Kim Jong-il's death in December, issued the same order during a separate tour to an islet on the east coast in recent days.

Kim "set forth the tasks for rounding off combat preparations and bolstering the combat capability," the dispatch said. (Yonhap)