South Korea has placed a priority on surveilling North Korea's possible launch of a long-range missile, an official said Tuesday.

Presidential spokesman Jeong Yeon-guk made the comments to reporters. He did not provide any further details, citing that it is an intelligence matter.

There has been recent speculation that North Korea could launch a long-range missile in an apparent response to the U.N.'s move to impose sanctions on the North for its fourth nuclear test on Jan. 6.

North Korea has a track record of test-firing long-range missiles after its three nuclear tests in 2006, 2009 and 2013.

Pyongyang has carried out a series of long-range rocket launches in recent years. In 2012, North Korea launched a satellite for what it claimed were peaceful purposes.

But South Korea, the United States and other regional powers suspect the North's satellite launch could be a covert test of its ballistic missile technology.

Jeong also said the government frequently holds National Security Council sessions to discuss the ongoing U.N. move to slap sanctions on North Korea.

Meanwhile, the Defense Ministry said it is closely monitoring a possible missile launch in North Korea.

A pro-North Korean website in the United States said Monday that when and where the North will launch a long-range missile will be totally decided by the North's leader Kim Jong-un.

"Our military is keeping close tabs on any signs of North Korean missile launch. Seoul and Washington are jointly operating a surveillance system," Moon Sang-gyun, a spokesman at the Ministry of National Defense, said at a regular press briefing. (Yonhap)