The United States reiterated its support for better relations between the two Koreas after North Korean leader Kim Jong-un made a surprising expression of his willingness to hold a summit with the South.

"We support improved inter-Korean relations," a State Department official said on condition of anonymity. 

In his New Year's address, the North's leader said he sees no reason not to hold a summit with the South as he called for the two sides to make a "a big shift, a big change" in their relations by promoting bilateral dialogue, negotiations, exchanges and contact.

It was unusual for the North's leader to openly express his willingness for a summit with the South.

South Korea said it assesses Kim's willingness as an "advanced attitude" and urged the North to accept an earlier proposal to hold high-level talks. Seoul made the dialogue offer earlier this week, saying it is ready to discuss all issues of concern.

The two Koreas held the first-ever summit of their leaders in 2000, leading to a significant warming of their relations and a second summit in 2007. But inter-Korean ties chilled again since a conservative president took power in the South in 2008. (Yonhap)