A rocket launch announced by North Korea is a "serious provocation," the Defense Ministry said Tuesday, adding that no signs of the planned launch have been seen so far.

"South Korea and the United States are jointly watching for all possibilities with regard to North Korea's (potential) long-range missile launch," ministry spokesman Kim Min-seok said in a briefing. "So far, no particular signs have been seen."

The launch will be "a serious provocation, a military threat and a violation of the U.N. resolutions banning the North from any acts in relation with the ballistic missile technology," Kim said.

North Korea's National Aerospace Development Administration said in a late night announcement a day earlier it plans to launch rockets as part of space research, cementing speculation over the country's moves to launch long-range missiles in celebration of the 70th anniversary of the Workers' Party of Korea on Oct. 10.

If the North pushes ahead with a launch, the government will examine whether the missile provocation constitutes an "abnormal situation," under which the South would resume its loudspeaker operations against the communist country, the spokesman said.

In the recent inter-Korean deal to defuse military tensions, Seoul agreed to suspend its propaganda broadcasts critical of North Korean leader Kim Jong-un under the condition no abnormal situations take place.

The deal implied that the broadcast operations could restart if North Korea launches military provocations.

The North also appears to be in the final stage of construction at its rocket launch facility in Dongchang-ri on its west coast border, Kim also added. (Yonhap)