South Korea sees no abnormal signs in North Korea which might have caused its leader, Kim Jong-un, to cancel his planned trip to Russia next week, Yonhap quoted a Defense Ministry official as saying.

On Thursday, a spokesman for Russian President Vladimir Putin told reporters that the North Korean leader will not visit Moscow for a celebration to mark the 70th anniversary of the end of World War II, saying that the decision "is related to internal Korean affairs."

South Korean and Russian officials had expected the leader of the reclusive nation to attend a military parade and hold a bilateral meeting with Putin.

It would have been his first foreign trip since taking office in 2011 upon the death of his father, Kim Jong-il.

"We don't believe that any notable internal affairs are taking place in North Korea (that are) serious enough to cause Kim not to attend the event," the official said, requesting anonymity.

With the South Korean government refusing to make official comments on its analysis of the cancellation, the official suggested that the decision is mainly caused by the leader's personality.

"It would be a heavy burden for the young, inexperienced leader to attend a major public event involving many other leaders from around the world," he said.

"He would have much less control than other bilateral visits."

Whether Kim will choose Russia as his first destination for a trip abroad has drawn keen attention, as his predecessors have never chosen any other country but China.