"The two leaders agreed Chairman Kim Jong-un's visit to Seoul would provide an additional momentum to their joint efforts to establish peace on the Korean Peninsula," Moon's chief press secretary Yoon Young-chan said of the summit.

Kim agreed to a Seoul visit to reciprocate Moon's trip to Pyongyang in September for their third inter-Korean summit.

Prospects of a fourth Moon-Kim summit seemed to dim when President Trump said his second meeting with Kim will likely take place next year.

Seoul officials have argued a South-North summit could be held at any time, regardless of when a proposed North Korea-U.S. summit would be held.

Still, many believed the North, at least, would want to make sure a second inter-Korean summit, before its leader's meeting with Trump, would not offend the U.S. president in any way.

Trump and Kim held their first meeting in June, followed by the latest inter-Korean summit held in Pyongyang in September.

"We make decisions based on what best serves us, but to North Korea, it may have to decide whether it would be better to hold (an inter-Korean summit) before or after the U.S.-North Korea summit," a ranking official from the South Korean presidential office Cheong Wa Dae said earlier.

Following Friday's meeting between Moon and Trump, the official noted the U.S. president may have offered his blessing for a Seoul meeting of the two Korean leaders before the year's end.

"I understand President Trump has been fully aware of the fact that a summit between the South and the North could be held within the year. President Trump must have been aware of that fact because we too have consistently said we look forward to Chairman Kim Jong-un's reciprocal visit to Seoul," the official told reporters, while asking not to be identified.

Seoul says no date has been set for Kim's visit, but has acknowledged making its own preparations just in case.

"Whether he will visit Seoul before the year's end is really only up to his own decision," a Cheong Wa Dae official said. (Yonhap)