The presidential office has reportedly decided it would be difficult for North Korean leader Kim Jong-un to visit Seoul by the year's end.

A high-ranking official from the top office told Yonhap News on Wednesday that Seoul now believes Kim's visit is unlikely to happen within the year, while another official said it's due to circumstances in the North.

Seoul has been pushing for Kim to make the reciprocal visit this year after he agreed to visit Seoul "at an early date" following the Pyongyang inter-Korean summit in September.

Pyongyang, however, is reported to have been cautious to clarify the timing of Kim's visit, out of apparent security concerns and amid its stalled denuclearization dialogue with Washington.

With the South remaining open to the visit, the question remains whether Kim will come to Seoul before his second meeting with U.S. President Donald Trump, which is expected to take place early next year.