South Korea voiced concerns Thursday over the instability of North Korea's decision-making process as Pyongyang has abruptly canceled an invitation for the U.N. chief to visit an inter-Korean industrial park in the North.
  

Without a reason being given, North Korea on Wednesday rescinded its permission for U.N. Secretary-General Ban Ki-moon's trip to the Kaesong Industrial Complex, which was originally supposed to be made on Thursday.
  

"South Korea has concerns about the North's unpredictability of its decision-making process," said a high-ranking official at the Ministry of Unification, requesting anonymity. "It is also regrettable that the North has been posing a threat to the South and making provocative remarks against it."
  

It was not the first time that Pyongyang has made a last-minute cancellation of a trip by high-profile figures to the North, including a previously scuttled visit by Robert King, U.S. special envoy for North Korean human rights.
  

Experts said that the North's move seemed to reflect the bellicose country's intention not to have dialogue with Seoul. The North also might be showing its anger against the South over what it believed were annoying comments about the North's rule.
  

Pyongyang claimed Wednesday that it has already built technology to make nuclear warheads small enough to fit on missiles, further escalating tensions sparked by its purported test-firing of a submarine-launched ballistic missile.
  

South Korea said that it will spare no efforts to hold dialogue with North Korea, although it will sternly respond to the North's provocations.
  

"The government still thinks that it would be good for the two Koreas to prepare for a joint commemorative event on Aug. 15 in a landmark year," the official said.
  

This year marks the 70th anniversary of Korea's liberation from Japan's 1910-45 colonial rule and an inter-Korean division. Korea's Liberation Day falls on Aug. 15.
  

South Korea is hoping that a joint event will be held in Seoul on the Liberation Day holiday, but the North has rejected Seoul's proposal for such an event. (Yonhap)