Since the beginning of last year, US President Donald Trump and North Korean leader Kim Jong-un have exchanged a total of 12 letters, said Minister for Unification of South Korea Kim Young Chul.

"Since 2018, chairman Kim has written eight letters to President Trump, and President Trump has written four letters to chairman Kim," CNA reported quoting the minister.

"I guess those leaders recognise the importance of resuming the dialogue between the two countries as they are constantly exchanging letters."

This weekend, Seoul is supposed to host the US president to resume the nuclear talks.

Earlier, South Korean President Moon Jae-in said that Pyongyang and Washington were conducting "backstage talks" to organize another meeting.