North Korean leader Kim Jong-un has written a "very warm" letter to US President Donald Trump requesting him for a second meeting, the White House has said, asserting that it is open to the idea and is already in the process of preparing ground for the high-profile summit.

The first meeting between the two leaders was held in Singapore in June. Talks between the US and North Korea have stalled since the leaders shook hands at the summit hailed as "historic". "President has received a letter from Kim Jong-un. It was a very warm, very positive letter. We won't release the full letter unless the North Korean leader agrees that we should," White House Press Secretary Sarah Sanders told reporters on Monday.