China's President Xi Jinping offered encouragement for South Korea's initiative to nurture peaceful engagement with North Korea, and Russia also expressed support, the South Korean official leading diplomatic efforts said on Thursday.
During the past week, National Security Office head Chung Eui-yong briefed officials in Beijing and Moscow following his dramatic success in arranging summits between the North Korean, South Korean and US leaders.
"Xi Jinping offered a Chinese phrase that says 'once hard ice melts, spring comes and flowers bloom' to describe the situation on the Korean peninsula and expressed his willingness to support the current situation," Chung told reporters on his return to Incheon International Airport.
North Korean leader Kim Jong Un told the South Korean delegation led by Chung that he was open to addressing denuclearising with the United States, an offer that led to US President Trump agreeing to meet Kim for a summit expected to happen sometime in May.
There was growing speculation on Thursday that Trump and Kim will meet Sweden, after its foreign ministry announced North Korea's Foreign Minister Ri Yong Ho was arriving imminently for two days of talks with his Swedish counterpart, Margot Wallstrom.
South Korean President Moon Jae-in is set to hold a summit with the North's Kim by the end of April.
The South's preparation committee for the inter-Korean summit, led by Moon's chief of staff Im Jong-seok, will hold its first official meeting on Friday, presidential spokesman Kim Eui-kyeom told a briefing.
The committee is comprised of presidential and government officials including the ministers of unification, foreign affairs and defence, Kim said.
Separately, a South Korean official said it was too early to discuss joint economic projects with Pyongyang.
The same official said China's top diplomat Yang Jiechi would visit Seoul on Tuesday for talks with South Korean security officials.