North Korean leader Kim Jong-un sent a letter of condolence to Japanese Prime Minister Fumio Kishida following a devastating earthquake in western Japan.

In the letter published by the regime's official state media Korean Central News Agency, Kim expressed his "deep sympathy and condolences" for the casualties and losses that Japan suffered in the earthquake on New Year's Day.

He referred to Kishida by a Korean honorific term reserved for national leaders.

Kim also expressed hope that the people affected by the quake overcome the aftermath quickly and return to normal lives.

North Korea has typically reserved such post-disaster letters of sympathy for "anti-American" nations such as Syria or Cuba.

The letter may be designed to help elevate Kim and North Korea's image by separating political and military problems from humanitarian issues.

It may also signal Pyongyang's desire to improve ties with Japan as a "new Cold War" takes root between South Korea, the United States and Japan on one side and North Korea, China and Russia on the other.