The North Korean leader is reported to have sent the personal message following the end of the Closing Ceremony in the capital.

"In the message the respected comrade Kim Jong-un extended heartfelt warm congratulations to general secretary Xi Jinping upon the splendid proceeding of the Beijing Winter Olympics as a novel and special grand sports festival," read a statement from the state-run Korean Central News Agency.

North Korea did not take part in the event after the International Olympic Committee suspended the country as punishment for refusing to take part at Tokyo 2020 over COVID-19 concerns.

Kim said that China has "left an indelible trace in the history of the Olympics with their indefatigable efforts" despite "unprecedently severe health crisis and the hostile forces' manoeuvres" and "demonstrated the stamina of China".

He also sent a message to Xi on the day of the Opening Ceremony.

"The successful opening of the Beijing Winter Olympics despite the worldwide health crisis and unprecedented severe circumstances is another great victory won by socialist China," said Kim on February 4.

Kim has been sending public messages to the Chinese President more frequently in recent years as Pyongyang pushes to strengthen ties with the powerhouse.

"The exchange of letters appears to be in part aimed at showing friendly exchanges between the leaders of North Korea and China can continue even at a time when in-person exchanges are difficult to take place," a Government official said, as reported by Yonhap News Agency.