Moon's appeal came after Kim threatened a demonstration of a "new strategic weapon" at a four-day ruling party meeting last week, where he never mentioned South Korea.

Since the breakdown of Kim's summit with US President Donald Trump in Hanoi last year, Pyongyang has repeatedly lashed out at the South, saying it has "nothing to talk" about any more with Seoul.

But Moon, who has long favoured engagement with the nuclear-armed North, doubled down on his dovish approach.

"I hope South and North Korea can make efforts together so that the conditions for Chairman Kim Jong Un's reciprocal visit can be arranged at an early date," Moon said in his annual New Year address.

The invitation for Kim to visit Seoul dates from the two leaders' last summit, in Pyongyang in September 2018, when the peninsula was basking in a diplomatic rapprochement.

"I'm willing to meet repeatedly and talk ceaselessly" with the North, Moon said in his speech, which was broadcast live.

He also suggested Pyongyang and Seoul should consult on fielding a unified team at the Tokyo Olympics in July, which would march together at the opening ceremony.

The two Koreas' athletes took part together at the opening and closing ceremonies of the Pyeongchang Winter Olympics in the South two years ago, and subsequently formed a series of joint teams in other events.

A possible joint bid for Seoul and Pyongyang to co-host the 2032 Summer Games was even mooted.

But their sporting ties have since entered a deep freeze -- North Korea gave up any prospect of its women's football team playing in Tokyo rather than take part in a qualifying competition in the South next month.