South Korea expressed hope Tuesday that North Korean leader Kim Jong-un's ongoing trip to China will be helpful to the denuclearization and peace process.

"The government expects that high-level exchanges between the North and China, including a meeting between Chairman Kim Jong-un and President Xi Jinping, will be able to contribute to the complete denuclearization and establishment of permanent peace on the Korean Peninsula," a foreign ministry official said, adding it's the government's formal response.

South Korea will continue efforts to foster the "virtuous cycle" of denuclearization and such diplomatic activities by the Koreas and regional powers, the official said.

Earlier in the day, the North's state media confirmed that Kim is on a four-day trip to China that started Monday. Chinese news outlets also carried similar reports.

Late Monday night, a diplomatic source told Yonhap News Agency that a special North Korean train, apparently carrying high-profile figures, crossed the border.

It's Kim's fourth-known trip to China since he took power in late 2011.

It came amid indications that his second summit with President Donald Trump may be imminent.

Trump told reporters that the two sides have been negotiating a summit venue and an announcement could be made in the near future.

Asked if Seoul was notified by Beijing of Kim's visit, the ministry official said the neighboring countries are "in close communication" on issues related to inter-Korean cooperation and North Korea-China exchanges. (Yonhap)