Kim Jong-un’s top negotiator is expected to travel to Washington this week in a potential sign that the momentum for a second summit between the North Korean leader and Donald Trump, the US president is building.

Kim Yong Chol, Pyongyang’s former spymaster, is likely to meet his US counterpart Mike Pompeo, the secretary of state, and possibly President Trump himself, reported CNN on Wednesday, although no firm details of meetings have been publicly announced.

“A lot of positive things are happening. He (President Trump) and Chairman Kim have established a good relationship, and conversations between the United States and North Korea continue,” a White House spokesperson told the news channel.

News of Mr Kim’s possible journey to the US had been reported earlier in the week by the South Korean press. According to the Yonhap newswire, he and two other North Korean officials have confirmed flights from Beijing to Washington on Thursday evening.

Mr Kim, one of Kim Jong-un’s most trusted advisers, also visited the White House last year, delivering an over-sized envelope with a letter from the North Korean leader less than two weeks before his first historic summit with Mr Trump in Singapore in June.