South Korea said Friday the Democratic People's Republic Korea (DPRK) will have to "take responsibility" for the alleged failed long-range rocket launch, which breached a UN ban.

Photo taken on April 8, 2012 shows the rocket for launching Kwangmyongsong-3 satellite installed on the launch pad in Tongchang-ri base, Democratic People's Republic of Korea (DPRK). [Xinhua]?

The 90-ton Unha-3 rocket was launched at 7:39 a.m. local time (2239 GMT Thursday) from the Tongchang-ri launch site but broke into some 20 pieces and fell into sea one or two minutes after the lift-off, according to the South Korean defense ministry.

So far, the DPRK has neither confirmed nor denied the launch.

Describing the launch as "a ballistic missile test" and a "serious threat," the South Korean defense ministry said the broken pieces landed in waters some 100 to 150 km off South Korea's western port city of Gunsan.

South Korea and Japan had vowed to shoot down the three-staged rocket or parts of it if they fall within their territory, prompting the DPRK to warn of "merciless punishment," but the debris fell in international waters.

Pyongyang has said the launch of a rocket-mounted satellite is to mark the birth centennial on April 15 of the country's founding father Kim Il Sung.

It has said the rocket launch is for peaceful purposes and would "not affect" other countries.

Seoul and Washington, among others, see it as a disguised long-range ballistic missile test that runs counter to a UN Security Council resolution and a recent food aid deal between Pyongyang and Washington under which the former halts nuclear and missile tests.

"North Korea (DPRK)'s long-range missile launch is a clear violation of UN Security Council resolution 1874 banning all launches using ballistic-missile technology, and is a provocative act that threatens peace and security of the Korean peninsula and the Northeast Asia," South Korean Foreign Minister Kim Sung-hwan said in a statement following a National Security Council meeting involving President Lee Myung-bak.

"North Korea will have to take responsibility (for the launch)," Kim said, adding the government is seeking a "comprehensive response" to potential nuclear and missile threats posed by its northern neighbor.

The UN Security Council is scheduled to meet Friday morning New York time to discuss responses to the rocket launch.

Meanwhile, South Korean media reported that South Korea is "tracking down" rocket debris to retrieve them.